media: drivers/media: don't set pix->priv = 0

The priv field of struct v4l2_pix_format shouldn't be set by drivers,
it's set by the v4l2 core instead to V4L2_PIX_FMT_PRIV_MAGIC.

Drop this from the few media drivers that still do this.

Note that the gspca patch is slightly more involved since some of the
sub-gspca drivers use the priv field internally.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
[hverkuil-cisco@xs4all.nl: fix clash in gspca between priv arg and priv variable]
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>