[media] v4l: omap4iss: Add enum_fmt_vid_cap ioctl support

List the pixel formats compatible with the active format currently
configured on the connected pad.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

diff --cc drivers/staging/media/omap4iss/iss_video.c
Simple merge