[media] media: v4l2-ctrls: add control for test pattern

add V4L2_CID_TEST_PATTERN of type menu, which determines
the internal test pattern selected by the device.

Signed-off-by: Lad, Prabhakar <prabhakar.lad@ti.com>
Signed-off-by: Manjunath Hadli <manjunath.hadli@ti.com>
Acked-by: Sakari Ailus <sakari.ailus@iki.fi>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

Documentation/DocBook/media/v4l/controls.xml

@@ -4267,6 +4267,16 @@ interface and may change in the future.</para>
 	    pixels / second.
 	    </entry>
 	  </row>
+	  <row>
+	    <entry spanname="id"><constant>V4L2_CID_TEST_PATTERN</constant></entry>
+	    <entry>menu</entry>
+	  </row>
+	  <row id="v4l2-test-pattern">
+	    <entry spanname="descr"> Some capture/display/sensor devices have
+	    the capability to generate test pattern images. These hardware
+	    specific test patterns can be used to test if a device is working
+	    properly.</entry>
+	  </row>
 	  <row><entry></entry></row>
 	</tbody>
       </tgroup>