[media] v4l: videobuf2: Fix typos in comments

The buffer flags are incorrectly referred to as V4L2_BUF_FLAGS_* instead
of V4L2_BUF_FLAG_* in comments. Fix it.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

include/media/videobuf2-core.h

@@ -356,8 +356,8 @@ struct v4l2_fh;
  * @buf_struct_size: size of the driver-specific buffer structure;
  *		"0" indicates the driver doesn't want to use a custom buffer
  *		structure type, so sizeof(struct vb2_buffer) will is used
- * @timestamp_flags: Timestamp flags; V4L2_BUF_FLAGS_TIMESTAMP_* and
- *		V4L2_BUF_FLAGS_TSTAMP_SRC_*
+ * @timestamp_flags: Timestamp flags; V4L2_BUF_FLAG_TIMESTAMP_* and
+ *		V4L2_BUF_FLAG_TSTAMP_SRC_*
  * @gfp_flags:	additional gfp flags used when allocating the buffers.
  *		Typically this is 0, but it may be e.g. GFP_DMA or __GFP_DMA32
  *		to force the buffer allocation to a specific memory zone.