[media] v4l2-ctrls: remove unclaimed v4l2_ctrl_add_ctrl() interface

v4l2_ctrl_add_ctrl() interface has no users since its introduction in
commit 0996517cf8ea ("V4L/DVB: v4l2: Add new control handling framework")
and its functionality is covered by v4l2_ctrl_new() and derivative
interfaces, so it is safe to remove the interface from the kernel.

Signed-off-by: Vladimir Zapolskiy <[e-mail]>
Signed-off-by: Hans Verkuil <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

Documentation/video4linux/v4l2-controls.txt

···
 	volume = v4l2_ctrl_new_std(&video_ctrl_handler, &ops, V4L2_CID_AUDIO_VOLUME, ...);
 	v4l2_ctrl_new_std(&video_ctrl_handler, &ops, V4L2_CID_BRIGHTNESS, ...);
 	v4l2_ctrl_new_std(&video_ctrl_handler, &ops, V4L2_CID_CONTRAST, ...);
-	v4l2_ctrl_add_ctrl(&radio_ctrl_handler, volume);
 
 What you should not do is make two identical controls for two handlers.
 For example:

drivers/media/v4l2-core/v4l2-ctrls.c

···
 }
 EXPORT_SYMBOL(v4l2_ctrl_new_int_menu);
 
-/* Add a control from another handler to this handler */
-struct v4l2_ctrl *v4l2_ctrl_add_ctrl(struct v4l2_ctrl_handler *hdl,
-					  struct v4l2_ctrl *ctrl)
-{
-	if (hdl == NULL || hdl->error)
-		return NULL;
-	if (ctrl == NULL) {
-		handler_set_err(hdl, -EINVAL);
-		return NULL;
-	}
-	if (ctrl->handler == hdl)
-		return ctrl;
-	return handler_new_ref(hdl, ctrl) ? NULL : ctrl;
-}
-EXPORT_SYMBOL(v4l2_ctrl_add_ctrl);
-
 /* Add the controls from another handler to our own. */
 int v4l2_ctrl_add_handler(struct v4l2_ctrl_handler *hdl,
 			  struct v4l2_ctrl_handler *add,

include/media/v4l2-ctrls.h

···
 			u32 id, u8 max, u8 def, const s64 *qmenu_int);
 
 /**
- * v4l2_ctrl_add_ctrl() - Add a control from another handler to this handler.
- * @hdl:	The control handler.
- * @ctrl:	The control to add.
- *
- * It will return NULL if it was unable to add the control reference.
- * If the control already belonged to the handler, then it will do
- * nothing and just return @ctrl.
- */
-struct v4l2_ctrl *v4l2_ctrl_add_ctrl(struct v4l2_ctrl_handler *hdl,
-					  struct v4l2_ctrl *ctrl);
-
-/**
  * v4l2_ctrl_add_handler() - Add all controls from handler @add to
  * handler @hdl.
  * @hdl:	The control handler.