video: fbdev: Check Standard Timing against DMT

Add the VESA Display Monitor Timing (DMT) table.
During parsing of Standard Timings, it compare the 2 byte STD code
with DMT to see what the VESA mode should be.  If there is no entry
in the vesa_modes table or no match found, it fallsback to the
GTF timings.

Signed-off-by: David Ung <davidu@nvidia.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>