These variables are now provided by the FindBabbleSim
cmake module, which finds them in the environment or thru
west.
Signed-off-by: Alberto Escolar Piedras <alberto.escolar.piedras@nordicsemi.no>
Let the board check for it instead, as it now does it
smarter and can try to find it using west if it was
fetched with the Zephyr manifest.
Signed-off-by: Alberto Escolar Piedras <alberto.escolar.piedras@nordicsemi.no>