lib: cmsis_rtos_v2: Additional Kconfig dependency
lib: cmsis_rtos_v2: Additional Kconfig dependency

Added Kconfig dependency that NUM_PREEMPT_PRIORITIES must be at least
osPriorityISR (56). This was enforced by a build assert message but not
decribed in the Kconfig.

Signed-off-by: Carlos Stuart <4ab5a1e66ba3b026677e9a622764fb5cd1361713@gmail.com>

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