media: sun6i: Add support for RGB565 formats

The CSI controller can take raw data from the data bus and output RGB565
format. The controller does not distinguish between RGB565 LE and BE.
Instead this is determined by the media bus format, i.e. the format or
order the sensor is sending data in.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Acked-by: Maxime Ripard <maxime.ripard@bootlin.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>