MPS2 AN521 has the wrong number of MPU region defined

Host environment

• Operating system: any
• OS/kernel version: any
• Architecture: any
• QEMU flavor: qemu-system-arm
• QEMU version: 7.0.0
• QEMU command line:

  qemu-system-arm -machine mps2-an521 -chardev stdio,id=con,mux=on -serial chardev:con -kernel ./build/zephyr/zephyr.elf

Emulated/Virtualized environment

• Operating system: Zephyr
• OS/kernel version: git
• Architecture: Arm

Description of problem

The AN521 is integrating SSE-200 on the MPS2+ FPGA prototyping board. The current implementation in qemu behaves as though there are 16MPU regions when it really only has 8, as describes as MPU_NS and MPU_S core configuration parameters in the SSE-200's Techincal Reference Manual.

Steps to reproduce

1. Prepare your Zephyr dev environment
2. fix boards/arm/mps2_an521/mps2_an521.dts to set arm,num-mpu-regions to the appropriate value of 8.
3. build a Zephyr test such as west build -p -b mps2_an521 -T tests/kernel/interrupt/arch.interrupt
4. run qemu-system-arm -machine mps2-an521 -chardev stdio,id=con,mux=on -serial chardev:con -kernel ./build/zephyr/zephyr.elf

Additional information

With matching MPU region number in QEMU and Zephyr's DTS, the application shows the test suite's progress & outcome. If there's a mismatch, the application will enter a fault and not display the expected traces.