arm: mvebu: theadorable: Enable video / LCD support with the new DM driver

With the new DM_VIDEO support in the Armada XP LCD driver, this patch
adds the needed DT node for the LCD controller to the theadorable dts
file. This DT property is not added to the Armada XP dtsi files, as this
LCD feature is pretty unusual for this SoC and I personally know of no
other board that uses this controller.

This patch also enables CONFIG_BMP_16BPP/24BPP/32BPP, as the "old" bmp
command supported these BMP files.

Signed-off-by: Stefan Roese <sr@denx.de>
Reviewed-by: Anatolij Gustschin <agust@denx.de>
Acked-by: Anatolij Gustschin <agust@denx.de>