dm: video: arm: rpi: Convert to use driver model for video

Adjust the video driver to work with driver model and move over existing
baords. There is no need to keep the old code.

We can also drop setting of CONFIG_FB_ADDR since driver model doesn't have
this problem.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Anatolij Gustschin <agust@denx.de>