[media] DocBook: update error code in videoc-streamon

Add description of ENOLINK error
Signed-off-by: Helen Mae Koike Fornazier <helen.koike@collabora.co.uk>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

Documentation/DocBook/media/v4l/vidioc-streamon.xml

@@ -123,6 +123,14 @@ synchronize with other events.</para>
 	  </para>
 	</listitem>
       </varlistentry>
+      <varlistentry>
+	<term><errorcode>ENOLINK</errorcode></term>
+	<listitem>
+	  <para>The driver implements Media Controller interface and
+	  the pipeline link configuration is invalid.
+	  </para>
+	</listitem>
+      </varlistentry>
     </variablelist>
   </refsect1>
 </refentry>