Bluetooth: Controller: Fix assert on advertise start
Bluetooth: Controller: Fix assert on advertise start

Using the shell application, starting advertisement while
the scanner is already running caused the controller to
assert.
The work which is supposed to set the radio active state to
active is not executed before the radio ISR resets the radio
active state, causing the assert. This can happen when a
newly started role is initialized to setup the radio trx and
the radio start code then detects that its hard realtime
instant has passed (as time was spent setting up the ticker
and ticker then firing thereafter) and hence cancels radio
trx.
Optionally (without this commit), dynamic calculation of
preparation time can be disabled by setting a constant time
in the define RADIO_TICKER_PREEMPT_PART_US in ctrl.c to
avoid the assert.

Change-id: Ib4415ec4b1bfdcc89aa0f3912e5a8fdd2e817fde
Signed-off-by: Vinayak Chettimada <614d8484483ffac23eafa42e03839fd19b3e69b8@nordicsemi.no>

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