media: Documentation: Drop deprecated bytesused == 0

The V4L2 API historically allowed buffers to be queued with bytesused
set to 0 on output devices, in which case the driver would use the
buffer length. This behaviour is deprecated, and videobuf2 prints a
warning message in the kernel log. Drop it from the documentation.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Reviewed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

Documentation/userspace-api/media/v4l/buffer.rst

@@ -187,10 +187,8 @@ struct v4l2_buffer
 	on the negotiated data format and may change with each buffer for
 	compressed variable size data like JPEG images. Drivers must set
 	this field when ``type`` refers to a capture stream, applications
-	when it refers to an output stream. If the application sets this
-	to 0 for an output stream, then ``bytesused`` will be set to the
-	size of the buffer (see the ``length`` field of this struct) by
-	the driver. For multiplanar formats this field is ignored and the
+	when it refers to an output stream. For multiplanar formats this field
+        is ignored and the
 	``planes`` pointer is used instead.
     * - __u32
       - ``flags``
@@ -327,10 +325,7 @@ struct v4l2_plane
       - ``bytesused``
       - The number of bytes occupied by data in the plane (its payload).
 	Drivers must set this field when ``type`` refers to a capture
-	stream, applications when it refers to an output stream. If the
-	application sets this to 0 for an output stream, then
-	``bytesused`` will be set to the size of the plane (see the
-	``length`` field of this struct) by the driver.
+	stream, applications when it refers to an output stream.
 
 	.. note::