media: v4l2-common: add has_alpha to v4l2_format_info

media: v4l2-common: add has_alpha to v4l2_format_info

Add a has_alpha value to the v4l2_format_info struct to indicate if the
format contains an alpha component. This information can currently not
be queried in a generic way, but might be useful for potential drivers
to properly setup alpha blending to copy or set the alpha value.
The implementation is based on the drm_format_info implementation.

Reviewed-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Signed-off-by: Sven Püschel <s.pueschel@pengutronix.de>
Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>