videomodes: Add (vesa) standard timings

videomodes: Add (vesa) standard timings

The timings for the modes defined in videomodes.c differ (significantly)
from vesa standard timings for these modes.

This commit adds a version with the proper std timings for these modes,
since I do not want to cause regressions, boards which want to use the standard
timings need to define CONFIG_VIDEO_STD_TIMINGS to get the new correct timings.

Since there is no std timing for 960x720 this commit uses the timing used
by the nvidia video drivers for 960x720, which uses a standard pixelclock
of 74.25 MHz rather then the weird 76.335... clock used by the old modes.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Anatolij Gustschin <agust@denx.de>