[media] v4l: add g_std_output callback to V4L2 subdev

Callback is used to acquire current analog TV standard from a subdev.
It is used to avoid keeping current standard in top-level driver.

Signed-off-by: Tomasz Stanislawski <t.stanislaws@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

include/media/v4l2-subdev.h

@@ -229,6 +229,9 @@ struct v4l2_subdev_audio_ops {
    s_std_output: set v4l2_std_id for video OUTPUT devices. This is ignored by
 	video input devices.
 
+   g_std_output: get current standard for video OUTPUT devices. This is ignored
+	by video input devices.
+
    g_tvnorms_output: get v4l2_std_id with all standards supported by video
 	OUTPUT device. This is ignored by video input devices.
 
@@ -269,6 +272,7 @@ struct v4l2_subdev_video_ops {
 	int (*s_routing)(struct v4l2_subdev *sd, u32 input, u32 output, u32 config);
 	int (*s_crystal_freq)(struct v4l2_subdev *sd, u32 freq, u32 flags);
 	int (*s_std_output)(struct v4l2_subdev *sd, v4l2_std_id std);
+	int (*g_std_output)(struct v4l2_subdev *sd, v4l2_std_id *std);
 	int (*querystd)(struct v4l2_subdev *sd, v4l2_std_id *std);
 	int (*g_tvnorms_output)(struct v4l2_subdev *sd, v4l2_std_id *std);
 	int (*g_input_status)(struct v4l2_subdev *sd, u32 *status);