cmake: do not run app data section aligning post-script for ARM
cmake: do not run app data section aligning post-script for ARM

Since the app_data_alignment.ld is not used anymore in ARM
builds, remove the need for running the script to auto-
generate it. The script now runs only for ARC builds.

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

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