hw/arm/mps2: Add CMSDK AHB GPIO peripherals as unimplemented devices

hw/arm/mps2: Add CMSDK AHB GPIO peripherals as unimplemented devices

Register the GPIO peripherals as unimplemented to better
follow their accesses, for example booting Zephyr:

  ----------------
  IN: arm_mps2_pinmux_init
  0x00001160:  f64f 0231  movw     r2, #0xf831
  0x00001164:  4b06       ldr      r3, [pc, #0x18]
  0x00001166:  2000       movs     r0, #0
  0x00001168:  619a       str      r2, [r3, #0x18]
  0x0000116a:  f24c 426f  movw     r2, #0xc46f
  0x0000116e:  f503 5380  add.w    r3, r3, #0x1000
  0x00001172:  619a       str      r2, [r3, #0x18]
  0x00001174:  f44f 529e  mov.w    r2, #0x13c0
  0x00001178:  f503 5380  add.w    r3, r3, #0x1000
  0x0000117c:  619a       str      r2, [r3, #0x18]
  0x0000117e:  4770       bx       lr
  cmsdk-ahb-gpio: unimplemented device write (size 4, value 0xf831, offset 0x18)
  cmsdk-ahb-gpio: unimplemented device write (size 4, value 0xc46f, offset 0x18)
  cmsdk-ahb-gpio: unimplemented device write (size 4, value 0x13c0, offset 0x18)

Reviewed-by: Peter Maydell <[email protected]>
Signed-off-by: Philippe Mathieu-Daudé <[email protected]>
Message-id: 20200617072539[email protected]
Signed-off-by: Peter Maydell <[email protected]>