[EFM32] Add delay after reset for greentea test runs.
[EFM32] Add delay after reset for greentea test runs.

The host-test resets the target by sending a UART break. After this, it takes some
time for the target to come back up. Without this timeout, the __sync packet
sent by greentea would not be retransmitted by the interface chip (i.e. it would never
reach the target). Testing on different devices indicates that 2 seconds delay
is sufficient for the device to reset and the  __sync packet to reach the target.

cvtsi2sd/mbed-os,radhika-raghavendran/mbed-os5.1-onsemi,maximmbed/mbed,HeadsUpDisplayInc/mbed,mikaleppanen/mbed-os,nRFMesh/mbed-os,ryankurte/mbed-os,jeremybrodt/mbed,mazimkhan/mbed-os,maximmbed/mbed,catiedev/mbed-os,NXPmicro/mbed,tung7970/mbed-os-1,YarivCol/mbed-os,svogl/mbed-os,mikaleppanen/mbed-os,theotherjimmy/mbed,jeremybrodt/mbed,fahhem/mbed-os,karsev/mbed-os,CalSol/mbed,HeadsUpDisplayInc/mbed,karsev/mbed-os,kl-cruz/mbed-os,Archcady/mbed-os,adustm/mbed,pradeep-gr/mbed-os5-onsemi,adamgreen/mbed,radhika-raghavendran/mbed-os5.1-onsemi,betzw/mbed-os,kl-cruz/mbed-os,infinnovation/mbed-os,theotherjimmy/mbed,fahhem/mbed-os,mmorenobarm/mbed-os,karsev/mbed-os,monkiineko/mbed-os,tung7970/mbed-os,adamgreen/mbed,kjbracey-arm/mbed,bulislaw/mbed-os,fanghuaqi/mbed,mmorenobarm/mbed-os,betzw/mbed-os,bulislaw/mbed-os,CalSol/mbed,CalSol/mbed,nRFMesh/mbed-os,arostm/mbed-os,rgrover/mbed,catiedev/mbed-os,netzimme/mbed-os,radhika-raghavendran/mbed-os5.1-onsemi,Archcady/mbed-os,ryankurte/mbed-os,svogl/mbed-os,fahhem/mbed-os,ryankurte/mbed-os,infinnovation/mbed-os,j-greffe/mbed-os,mmorenobarm/mbed-os,fvincenzo/mbed-os,j-greffe/mbed-os,bcostm/mbed-os,fahhem/mbed-os,maximmbed/mbed,andcor02/mbed-os,betzw/mbed-os,kl-cruz/mbed-os,maximmbed/mbed,monkiineko/mbed-os,pradeep-gr/mbed-os5-onsemi,geky/mbed,mmorenobarm/mbed-os,j-greffe/mbed-os,j-greffe/mbed-os,karsev/mbed-os,jeremybrodt/mbed,catiedev/mbed-os,rgrover/mbed,adustm/mbed,Archcady/mbed-os,NXPmicro/mbed,screamerbg/mbed,andcor02/mbed-os,adustm/mbed,Archcady/mbed-os,mmorenobarm/mbed-os,catiedev/mbed-os,NXPmicro/mbed,fvincenzo/mbed-os,kjbracey-arm/mbed,screamerbg/mbed,geky/mbed,cvtsi2sd/mbed-os,Archcady/mbed-os,monkiineko/mbed-os,tung7970/mbed-os,fanghuaqi/mbed,kl-cruz/mbed-os,c1728p9/mbed-os,HeadsUpDisplayInc/mbed,svogl/mbed-os,mikaleppanen/mbed-os,RonEld/mbed,mikaleppanen/mbed-os,radhika-raghavendran/mbed-os5.1-onsemi,mbedmicro/mbed,nvlsianpu/mbed,nRFMesh/mbed-os,fanghuaqi/mbed,j-greffe/mbed-os,arostm/mbed-os,monkiineko/mbed-os,andreaslarssonublox/mbed,bulislaw/mbed-os,rgrover/mbed,CalSol/mbed,adustm/mbed,arostm/mbed-os,nvlsianpu/mbed,rgrover/mbed,cvtsi2sd/mbed-os,mbedmicro/mbed,YarivCol/mbed-os,netzimme/mbed-os,nRFMesh/mbed-os,arostm/mbed-os,screamerbg/mbed,bcostm/mbed-os,screamerbg/mbed,nvlsianpu/mbed,arostm/mbed-os,andreaslarssonublox/mbed,adamgreen/mbed,netzimme/mbed-os,nvlsianpu/mbed,fahhem/mbed-os,infinnovation/mbed-os,netzimme/mbed-os,fvincenzo/mbed-os,c1728p9/mbed-os,Archcady/mbed-os,svastm/mbed,mikaleppanen/mbed-os,ryankurte/mbed-os,bcostm/mbed-os,catiedev/mbed-os,netzimme/mbed-os,YarivCol/mbed-os,fvincenzo/mbed-os,svastm/mbed,theotherjimmy/mbed,nvlsianpu/mbed,adamgreen/mbed,tung7970/mbed-os-1,HeadsUpDisplayInc/mbed,rgrover/mbed,infinnovation/mbed-os,radhika-raghavendran/mbed-os5.1-onsemi,jeremybrodt/mbed,svastm/mbed,RonEld/mbed,arostm/mbed-os,mbedmicro/mbed,kjbracey-arm/mbed,radhika-raghavendran/mbed-os5.1-onsemi,NXPmicro/mbed,geky/mbed,catiedev/mbed-os,svastm/mbed,YarivCol/mbed-os,j-greffe/mbed-os,kjbracey-arm/mbed,geky/mbed,svogl/mbed-os,andcor02/mbed-os,RonEld/mbed,fanghuaqi/mbed,bulislaw/mbed-os,monkiineko/mbed-os,bcostm/mbed-os,c1728p9/mbed-os,HeadsUpDisplayInc/mbed,NXPmicro/mbed,jeremybrodt/mbed,infinnovation/mbed-os,ryankurte/mbed-os,andreaslarssonublox/mbed,c1728p9/mbed-os,svogl/mbed-os,kl-cruz/mbed-os,mmorenobarm/mbed-os,andcor02/mbed-os,NXPmicro/mbed,monkiineko/mbed-os,pradeep-gr/mbed-os5-onsemi,maximmbed/mbed,mazimkhan/mbed-os,infinnovation/mbed-os,geky/mbed,betzw/mbed-os,andcor02/mbed-os,fahhem/mbed-os,tung7970/mbed-os-1,svogl/mbed-os,mazimkhan/mbed-os,mazimkhan/mbed-os,tung7970/mbed-os,RonEld/mbed,cvtsi2sd/mbed-os,CalSol/mbed,pradeep-gr/mbed-os5-onsemi,bcostm/mbed-os,cvtsi2sd/mbed-os,YarivCol/mbed-os,theotherjimmy/mbed,tung7970/mbed-os,mazimkhan/mbed-os,pradeep-gr/mbed-os5-onsemi,adustm/mbed,bulislaw/mbed-os,nRFMesh/mbed-os,adustm/mbed,adamgreen/mbed,mbedmicro/mbed,andreaslarssonublox/mbed,screamerbg/mbed,c1728p9/mbed-os,RonEld/mbed,adamgreen/mbed,CalSol/mbed,screamerbg/mbed,mbedmicro/mbed,ryankurte/mbed-os,karsev/mbed-os,nRFMesh/mbed-os,tung7970/mbed-os-1,maximmbed/mbed,fvincenzo/mbed-os,fanghuaqi/mbed,betzw/mbed-os,theotherjimmy/mbed,theotherjimmy/mbed,nvlsianpu/mbed,karsev/mbed-os,pradeep-gr/mbed-os5-onsemi,bulislaw/mbed-os,c1728p9/mbed-os,RonEld/mbed,mazimkhan/mbed-os,tung7970/mbed-os-1,kl-cruz/mbed-os,YarivCol/mbed-os,svastm/mbed,cvtsi2sd/mbed-os,tung7970/mbed-os,bcostm/mbed-os,netzimme/mbed-os,HeadsUpDisplayInc/mbed,betzw/mbed-os,mikaleppanen/mbed-os,andcor02/mbed-os,andreaslarssonublox/mbed