board: ge: mx53ppd: enable DM_VIDEO

Enable DM_VIDEO for mx53ppd.
Enable DM_REGULATOR_FIXED and DM_PWM for the backlight.
Remove unused MX53PPD_LCD_POWER.
Remove old (incorrect) setup_iomux_lcd.
Enable backlight via display enable handler.
Use cls command to initiate display in HW agnostic manner.
Modify `failbootcmd' to use lcdputs.

Signed-off-by: Ian Ray <ian.ray@ge.com>
Signed-off-by: Robert Beckett <bob.beckett@collabora.com>