[media] v4l2-subdev.h: Improve documentation

This header were poorly documented, and weren't using the
kernel-doc format. Document everything but the macros using
the right format.

While here, also fix the other comments to match the
Linux CodingStyle.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

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

@@ -621,16 +621,6 @@ void v4l2_subdev_init(struct v4l2_subdev *sd, const struct v4l2_subdev_ops *ops)
 }
 EXPORT_SYMBOL(v4l2_subdev_init);
 
-/**
- * v4l2_subdev_notify_event() - Delivers event notification for subdevice
- * @sd: The subdev for which to deliver the event
- * @ev: The event to deliver
- *
- * Will deliver the specified event to all userspace event listeners which are
- * subscribed to the v42l subdev event queue as well as to the bridge driver
- * using the notify callback. The notification type for the notify callback
- * will be V4L2_DEVICE_NOTIFY_EVENT.
- */
 void v4l2_subdev_notify_event(struct v4l2_subdev *sd,
 			      const struct v4l2_event *ev)
 {