ipq40xx: Add reserved memory for WPJ428

ipq40xx: Add reserved memory for WPJ428

The APPSBL and anything after that it not allowed to touch some of the
memory regions which are used by other components. Still trying to write to
the memory can lead to sudden device restarts

  (IPQ40xx) # mw 87e80000 0
  data abort
  pc : [<873149f8>]          lr : [<87308578>]
  sp : 86edfc28  ip : 86ef4412     fp : 00000000
  r10: 00000000  r9 : 00000000     r8 : 86edff68
  r7 : 00000003  r6 : 8737e624     r5 : 86ef4420  r4 : 8736c154
  r3 : 00000000  r2 : 00000010     r1 : 00000000  r0 : 00000000
  Flags: nZCv  IRQs off  FIQs off  Mode SVC_32
  Resetting CPU ...

The device manufacturer only provided a very rough list of regions:

* rsvd1:     0x87000000 0x500000
* wifi_dump: 0x87500000 0x600000
* rsvd2:     0x87b00000 0x500000

A more detailed list for devices using the AP.DK reference design memory
maps was provided by Roman Yeryomin <roman@advem.lv> in commit 56f2df879fd
("ipq806x: ipq4019: add ap-dk01.1-c1 board support"):

* apps_bl:          0x87000000 0x400000
* sbl:              0x87400000 0x100000
* cnss_debug:       0x87500000 0x600000
* cpu_context_dump: 0x87b00000 0x080000
* tz_apps:          0x87b80000 0x280000
* smem:             0x87e00000 0x080000
* tz:               0x87e80000 0x180000

The u-boot function ipq_fdt_mem_rsvd_fixup seems to suggest that only the
rsvd2 (tz_apps, smem, tz) should be protected. All other regions would have
been removed by it when CONFIG_QCA_APPSBL_DLOAD is not enabled. This allows
to reduce the 16MB reserved memory region to only 4.5MB.

Signed-off-by: Sven Eckelmann <sven.eckelmann@openmesh.com>