arch: arm: macro API for defining non-secure entry functions
arch: arm: macro API for defining non-secure entry functions

This commit introduces an internal ARM macro API to allow the
TrustZone user to define Non-Secure entry functions.

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

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