soc: arm: Kconfig: Add more nrf flash protection block sizes

Add
- NRF_MPU_FLASH_REGION_SIZE
- NRF_BPROT_FLASH_REGION_SIZE
- NRF_ACL_FLASH_REGION_SIZE

NRF_SPU_FLASH_REGION_SIZE is already available.

Signed-off-by: Øyvind Rønningstad <oyvind.ronningstad@nordicsemi.no>