[media] v4l2: Fix the type of V4L2_CID_TUNE_PREEMPHASIS in the documentation

Change the type of V4L2_CID_TUNE_PREEMPHASIS from 'integer' to 'enum
v4l2_preemphasis'
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

Documentation/DocBook/media/v4l/controls.xml

@@ -3854,7 +3854,7 @@ in Hz. The range and step are driver-specific.</entry>
 	  </row>
 	  <row>
 	    <entry spanname="id"><constant>V4L2_CID_TUNE_PREEMPHASIS</constant>&nbsp;</entry>
-	    <entry>integer</entry>
+	    <entry>enum v4l2_preemphasis</entry>
 	  </row>
 	  <row id="v4l2-preemphasis"><entry spanname="descr">Configures the pre-emphasis value for broadcasting.
 A pre-emphasis filter is applied to the broadcast to accentuate the high audio frequencies.