ARM: 7824/1: update advice on kernel, initramfs and FDT load address.

  - Recommend that the kernel be placed under 128MiB, this is required if
    CONFIG_AUTO_ZRELADDR=y and good (or at least not bad) advice even if
    CONFIG_AUTO_ZRELADDR=n.
  - Recommend that a zImage kernel be placed above 32MiB, this avoids the need
    to relocate prior to decompression, which can speed up boot.
  - Add basic info on the requirements when loading a raw (non-zImage) kernel
    which are stricter than the zImage requirements.
  - Recommend that the DTB be placed after the 128MiB boundary, avoiding any
    potential conflict with the kernel decompressor, and within the lowmem
    region.  In practice it could follow the kernel loaded after 32MiB,
    assuming the kernel decompesses to less than 32MiB, but the 128MiB
    recommendation is simple and unambiguous.
  - Add similar recommendation regarding initramfs.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: Wil...