[media] v4l: drop v4l2_buffer.input and V4L2_BUF_FLAG_INPUT

Remove input field in struct v4l2_buffer and flag V4L2_BUF_FLAG_INPUT which
tells the former is valid. The flag is used by no driver currently.

Also change the documentation accordingly.

Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/Documentation/DocBook/media/v4l/compat.xml b/Documentation/DocBook/media/v4l/compat.xml
index ea42ef8..a8b3749 100644
--- a/Documentation/DocBook/media/v4l/compat.xml
+++ b/Documentation/DocBook/media/v4l/compat.xml
@@ -2458,6 +2458,18 @@
       </orderedlist>
     </section>
 
+    <section>
+      <title>V4L2 in Linux 3.5</title>
+      <orderedlist>
+	<listitem>
+	  <para>Replaced <structfield>input</structfield> in
+	  <structname>v4l2_buffer</structname> by
+	  <structfield>reserved2</structfield> and removed
+	  <constant>V4L2_BUF_FLAG_INPUT</constant>.</para>
+	</listitem>
+      </orderedlist>
+    </section>
+
     <section id="other">
       <title>Relation of V4L2 to other Linux multimedia APIs</title>