[PATCH] ps3: Preallocate bootmem memory for ps3fb

Preallocate bootmem memory for the PS3 frame buffer device, which needs a
large block of physically-contiguous memory. The size of this memory block is
configurable:
  - The config option CONFIG_FB_PS3_DEFAULT_SIZE_M allows to specify the
    default amount of memory (in MiB) allocated to the virtual frame buffer.
  - The early boot parameter `ps3fb=xxx' allows to override the default value.
    It will be rounded up to a multiple of 1 MiB, if needed.

Signed-off-by: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>
Signed-off-by: Geoff Levand <geoffrey.levand@am.sony.com>
Cc: James Simmons <jsimmons@infradead.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>