[media] V4L: JPEG class documentation corrections

This patch fixes following compilation warning:
Error: no ID for constraint linkend: v4l2-jpeg-chroma-subsampling.

and adds missing JPEG control class at the Table A.58.
Signed-off-by: Sylwester Nawrocki <sylvester.nawrocki@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

Documentation/DocBook/media/v4l/controls.xml

@@ -3486,7 +3486,7 @@ interface and may change in the future.</para>
 	    from RGB to Y'CbCr color space.
 	    </entry>
 	  </row>
-	  <row>
+	  <row id = "v4l2-jpeg-chroma-subsampling">
 	    <entrytbl spanname="descr" cols="2">
 	      <tbody valign="top">
 		<row>

Documentation/DocBook/media/v4l/vidioc-g-ext-ctrls.xml

@@ -265,6 +265,13 @@ These controls are described in <xref
 These controls are described in <xref
 		linkend="flash-controls" />.</entry>
 	  </row>
+	  <row>
+	    <entry><constant>V4L2_CTRL_CLASS_JPEG</constant></entry>
+	    <entry>0x9d0000</entry>
+	    <entry>The class containing JPEG compression controls.
+These controls are described in <xref
+		linkend="jpeg-controls" />.</entry>
+	  </row>
 	</tbody>
       </tgroup>
     </table>