[media] vb2: Allow queuing OUTPUT buffers with zeroed 'bytesused'

Modify the bytesused/data_offset check to not fail if both bytesused
and data_offset is set to 0. This should minimize possible issues in
existing applications which worked before we enforced the plane lengths
for output buffers checks introduced in commit 8023ed09cb278004a2
"videobuf2-core: Verify planes lengths for output buffers"

Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

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

@@ -353,7 +353,9 @@ static int __verify_length(struct vb2_buffer *vb, const struct v4l2_buffer *b)
 
 			if (b->m.planes[plane].bytesused > length)
 				return -EINVAL;
-			if (b->m.planes[plane].data_offset >=
+
+			if (b->m.planes[plane].data_offset > 0 &&
+			    b->m.planes[plane].data_offset >=
 			    b->m.planes[plane].bytesused)
 				return -EINVAL;
 		}