media: v4l2-ctrls: Fix typo in VP8 comment

The comment for the VP8 loop filter flags uses the partially wrong name
for the flags. Unlike the other VP8 flag names, the loop filter flag names
don't have "_FLAG" in them. Change the comment so that it matches the
actual flag definitions in the header.

Signed-off-by: Deborah Brouwer <deborah.brouwer@collabora.com>
Reviewed-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>