uboot-phytec

board: imx53: Always disable display before starting kernel

This patch prevents from the situation where we may end up with garbage
displayed on the LCD panel.

Such situation occurs when one performs "reboot -f" in Linux and then
stop in U-boot (or observe the garbage on the screen during boot up).

To prevent from such situation - the PWM pin is configured as GPIO and set
to LOW.

Signed-off-by: Lukasz Majewski <lukma@denx.de>