[media] vb2: Fix vb2_core_dqbuf() kernel-doc

The kernel-doc has the wrong function name and also the pindex
parameter is missing in the documentation.

Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/media/v4l2-core/videobuf2-core.c

@@ -1733,8 +1733,9 @@ static void __vb2_dqbuf(struct vb2_buffer *vb)
 }
 
 /**
- * vb2_dqbuf() - Dequeue a buffer to the userspace
+ * vb2_core_dqbuf() - Dequeue a buffer to the userspace
  * @q:		videobuf2 queue
+ * @pindex:	pointer to the buffer index. May be NULL
  * @pb:		buffer structure passed from userspace to vidioc_dqbuf handler
  *		in driver
  * @nonblocking: if true, this call will not sleep waiting for a buffer if no