video: mxsfb: fix broken videomode selection

video: mxsfb: fix broken videomode selection

Currently the driver re-implements the code found in of_get_videomode()
except for the fact that the latter honors the 'native-mode' property
to select a spcific video timing from the list of possible timings.
The driver builds up a list of all video timings, but uses only the
last mode from the list anyway. While building the list it incorrectly
OR's the 'pixelclk-active' and 'de-active' flags of all modes into
single flags, possibly leading to a wrong pixelclock or data-enable
polarity setting.

Fix this by using the of_get_videomode() directly with the
OF_USE_NATIVE_MODE flag.

Since all current dts files only have one entry in their
display-timings node, this bug was not apparent and the fix does not
change the driver's behaviour for the current users.

Signed-off-by: Lothar Waßmann <LW@KARO-electronics.de>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>