Entity controls should get_cur using an entity-defined function
instead of via a query. Fix this in uvc_ctrl_set.

Fixes: 65900c58 ("media: uvcvideo: Allow entity-defined get_info and get_cur")
Signed-off-by: Yunke Cao <yunkec@google.com>
Reviewed-by: Ricardo Ribalda <ribalda@chromium.org>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>