This adds the actual VGA DAC bridge that is used in the
Versatile AB, and sets the mode to 640x480 VGA and
routes the CLCD pads appropriately.

Cc: Liviu Dudau <liviu.dudau@arm.com>
Cc: Mali DP Maintainers <malidp@foss.arm.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>