media: media-types.rst: codec entities can have more than one source pad

Some decoders and encoders can potentially have more than one source pad,
so update the description to say 'at least one source pad'.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

Documentation/media/uapi/mediactl/media-types.rst

@@ -192,12 +192,13 @@ Types and flags used to represent the media graph elements
 
     *  -  ``MEDIA_ENT_F_PROC_VIDEO_ENCODER``
        -  Video (MPEG, HEVC, VPx, etc.) encoder. An entity capable of
-          compressing video frames. Must have one sink pad and one source pad.
+          compressing video frames. Must have one sink pad and at least
+	  one source pad.
 
     *  -  ``MEDIA_ENT_F_PROC_VIDEO_DECODER``
        -  Video (MPEG, HEVC, VPx, etc.) decoder. An entity capable of
           decompressing a compressed video stream into uncompressed video
-	  frames. Must have one sink pad and one source pad.
+	  frames. Must have one sink pad and at least one source pad.
 
     *  -  ``MEDIA_ENT_F_VID_MUX``
        - Video multiplexer. An entity capable of multiplexing must have at