soc: arm: introduce Kconfig option for Nordic IDAU
soc: arm: introduce Kconfig option for Nordic IDAU

This commit introduces a new Kconfig symbol to signify
that a CPU implements the Nordic-specific security
attribution unit. The symbol is meant to be selected
by Nordic SoCs that implement the System Protection
Unit (SPU) peripheral.

Signed-off-by: Ioannis Glaropoulos <5921cc8bab7e1d4329f52fd8f6268f9692e3de80@nordicsemi.no>

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