media: ov6650: Fix .get_fmt() V4L2_SUBDEV_FORMAT_TRY support

commit 39034bb0 upstream.

Commit da298c6d ("[media] v4l2: replace video op g_mbus_fmt by pad
op get_fmt") converted a former ov6650_g_fmt() video operation callback
to an ov6650_get_fmt() pad operation callback.  However, the converted
function disregards a format->which flag that pad operations should
obey and always returns active frame format settings.

That can be fixed by always responding to V4L2_SUBDEV_FORMAT_TRY with
-EINVAL, or providing the response from a pad config argument, likely
updated by a former user call to V4L2_SUBDEV_FORMAT_TRY .set_fmt().
Since implementation of the latter is trivial, go for it.

Fixes: da298c6d ("[media] v4l2: replace video op g_mbus_fmt by pad op get_fmt")
Signed-off-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>