[PATCH] gbefb: Set default of FB_GBE_MEM to 4 MB

Allocating more than 4 MB memory for the GBE (SGI O2) framebuffer completely
breakfs gbefb support at the moment.  According to comments on #mipslinux,
more than 4 MB has never worked correctly in Linux.  Therefore, the default
should be 4 MB.

Signed-off-by: Martin Michlmayr <tbm@cyrius.com>
Signed-off-by: Antonino Daplas <adaplas@pol.net>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>