Bluetooth: Mesh: Depend Mesh upon Observer and Broadcaster roles
Bluetooth: Mesh: Depend Mesh upon Observer and Broadcaster roles

This adds dependency upon BT_BROADCASTER and BT_OBSERVER roles.
Those are necessary to implement Mesh device.

Signed-off-by: Mariusz Skamra <c73850bd0bf85e95dce44c2ce1418ca55c1b6c5d@codecoup.pl>

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