OLPC: gxfb/lxfb: add DCON panel modes to framebuffer drivers

Since there's no way to autodetect panel modes, we're forced to hardcode them
in the driver and add a big fat #ifdef.  The OLPC DCON needs a specific mode
line (at 1200x900).  This adds it to both gxfb and lxfb.

(Jordan said: We could probably detect the panel mode, but there isn't any
reason to since the panel timings are well known and won't change.  While OFW
detection would be good computer science fu, it would be a wasted effort since
its so easy to hard code them into the table.)

Signed-off-by: Andres Salomon <dilinger@debian.org>
Cc: Jordan Crouse <jordan.crouse@amd.com>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>