net: tcp: don't assume TCP_FIN buffers are NET_DROP
net: tcp: don't assume TCP_FIN buffers are NET_DROP

Since we default to a return value of NET_DROP, we
can remove the automatic NET_DROP in the TCP_FIN block.

The return value will be set to NET_OK by packet_received()
if appropriate data is found which needs to be sent to
the callback.

Change-Id: Ib2634ba34440ca7053a4e98bf80f12cf6fbbd361
Signed-off-by: Michael Scott <087571639a1dbb4ff1803c64e3643475ba482686@linaro.org>

sharronliu/zephyr,bboozzoo/zephyr,Vudentz/zephyr,kraj/zephyr,holtmann/zephyr,Vudentz/zephyr,nashif/zephyr,nashif/zephyr,ldts/zephyr,finikorg/zephyr,aceofall/zephyr-iotos,galak/zephyr,punitvara/zephyr,bigdinotech/zephyr,explora26/zephyr,GiulianoFranchetto/zephyr,ldts/zephyr,GiulianoFranchetto/zephyr,aceofall/zephyr-iotos,bigdinotech/zephyr,pklazy/zephyr,erwango/zephyr,fbsder/zephyr,sharronliu/zephyr,pklazy/zephyr,GiulianoFranchetto/zephyr,galak/zephyr,erwango/zephyr,nashif/zephyr,rsalveti/zephyr,ldts/zephyr,ldts/zephyr,fractalclone/zephyr-riscv,mbolivar/zephyr,holtmann/zephyr,finikorg/zephyr,runchip/zephyr-cc3200,bigdinotech/zephyr,punitvara/zephyr,zephyriot/zephyr,ldts/zephyr,runchip/zephyr-cc3200,runchip/zephyr-cc3200,rsalveti/zephyr,finikorg/zephyr,Vudentz/zephyr,nashif/zephyr,zephyriot/zephyr,explora26/zephyr,explora26/zephyr,galak/zephyr,explora26/zephyr,fractalclone/zephyr-riscv,tidyjiang8/zephyr-doc,fbsder/zephyr,mbolivar/zephyr,sharronliu/zephyr,mbolivar/zephyr,zephyrproject-rtos/zephyr,pklazy/zephyr,nashif/zephyr,holtmann/zephyr,pklazy/zephyr,kraj/zephyr,bboozzoo/zephyr,zephyrproject-rtos/zephyr,punitvara/zephyr,aceofall/zephyr-iotos,GiulianoFranchetto/zephyr,galak/zephyr,fractalclone/zephyr-riscv,zephyriot/zephyr,sharronliu/zephyr,tidyjiang8/zephyr-doc,holtmann/zephyr,kraj/zephyr,aceofall/zephyr-iotos,finikorg/zephyr,punitvara/zephyr,bboozzoo/zephyr,mbolivar/zephyr,rsalveti/zephyr,fractalclone/zephyr-riscv,Vudentz/zephyr,runchip/zephyr-cc3220,GiulianoFranchetto/zephyr,bboozzoo/zephyr,zephyrproject-rtos/zephyr,pklazy/zephyr,runchip/zephyr-cc3220,erwango/zephyr,sharronliu/zephyr,kraj/zephyr,tidyjiang8/zephyr-doc,fbsder/zephyr,runchip/zephyr-cc3220,rsalveti/zephyr,tidyjiang8/zephyr-doc,explora26/zephyr,erwango/zephyr,zephyriot/zephyr,fbsder/zephyr,fbsder/zephyr,zephyrproject-rtos/zephyr,runchip/zephyr-cc3220,rsalveti/zephyr,zephyriot/zephyr,fractalclone/zephyr-riscv,runchip/zephyr-cc3200,tidyjiang8/zephyr-doc,holtmann/zephyr,kraj/zephyr,galak/zephyr,Vudentz/zephyr,bigdinotech/zephyr,mbolivar/zephyr,bigdinotech/zephyr,Vudentz/zephyr,runchip/zephyr-cc3200,erwango/zephyr,bboozzoo/zephyr,finikorg/zephyr,runchip/zephyr-cc3220,aceofall/zephyr-iotos,zephyrproject-rtos/zephyr,punitvara/zephyr