documentation: media: Add documentation for new RGB and YUV bus formats

documentation: media: Add documentation for new RGB and YUV bus formats

Add documentation for added Bus Formats to describe RGB and YUV formats used
as input to the Synopsys DesignWare HDMI TX Controller.

Acked-by: Hans Verkuil <[email protected]>
Reviewed-by: Archit Taneja <[email protected]>
Acked-by: Mauro Carvalho Chehab <[email protected]>
Signed-off-by: Neil Armstrong <[email protected]>
Signed-off-by: Sean Paul <[email protected]>
Link: http://patchwork.freedesktop.org/patch/msgid/[email protected]