nrf52_bsim: declare BSIM_OUT_PATH as required env var
nrf52_bsim: declare BSIM_OUT_PATH as required env var

Do not use with sanitycheck if BSIM_OUT_PATH is not defined.

Signed-off-by: Anas Nashif <0d9952ec84ac43c159f6b7e7ed99a9080c00dd6e@intel.com>

punitvara/zephyr,GiulianoFranchetto/zephyr,finikorg/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,GiulianoFranchetto/zephyr,zephyrproject-rtos/zephyr,GiulianoFranchetto/zephyr,ldts/zephyr,Vudentz/zephyr,explora26/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,ldts/zephyr,punitvara/zephyr,finikorg/zephyr,punitvara/zephyr,galak/zephyr,ldts/zephyr,galak/zephyr,nashif/zephyr,GiulianoFranchetto/zephyr,finikorg/zephyr,Vudentz/zephyr,Vudentz/zephyr,galak/zephyr,nashif/zephyr,Vudentz/zephyr,ldts/zephyr,GiulianoFranchetto/zephyr,Vudentz/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,finikorg/zephyr,explora26/zephyr,explora26/zephyr,nashif/zephyr,punitvara/zephyr,zephyrproject-rtos/zephyr,explora26/zephyr,explora26/zephyr,punitvara/zephyr,nashif/zephyr,ldts/zephyr,finikorg/zephyr