The v4l2-ioctl core now only allows buffer types for which the
corresponding ->vidioc_try_fmt_xxx() methods are defined to be used with
vidioc_(g|s)_parm.

The driver was only allowing VIDEO_CAPTURE buffers for g_parm, but since
the driver defines ->vidioc_try_fmt_vid_overlay() it will now allow
VIDEO_OVERLAY buffers as well.  This should be fine as the fields the
driver fills in, readbuffers and frame rate, aren't wrong for VIDEO_OVERLAY
buffers.
Signed-off-by: Trent Piepho <xyzzy@speakeasy.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>