[media] V4L: Add v4l2_ctrl_subdev_log_status() helper function

This patch adds a v4l2 core helper function that can be used as
the log_status handler for subdevs that only need to log state
of the v4l2 controls owned by the subdev's control handler.

Signed-off-by: Sylwester Nawrocki <sylvester.nawrocki@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/include/media/v4l2-ctrls.h b/include/media/v4l2-ctrls.h
index 1e84946..f00d42b 100644
--- a/include/media/v4l2-ctrls.h
+++ b/include/media/v4l2-ctrls.h
@@ -659,4 +659,7 @@
 int v4l2_ctrl_subdev_subscribe_event(struct v4l2_subdev *sd, struct v4l2_fh *fh,
 				     struct v4l2_event_subscription *sub);
 
+/* Log all controls owned by subdev's control handler. */
+int v4l2_ctrl_subdev_log_status(struct v4l2_subdev *sd);
+
 #endif