[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/io.xml b/Documentation/DocBook/media/v4l/io.xml
index fd6aca2..1885cc0 100644
--- a/Documentation/DocBook/media/v4l/io.xml
+++ b/Documentation/DocBook/media/v4l/io.xml
@@ -683,14 +683,12 @@
 	  </row>
 	  <row>
 	    <entry>__u32</entry>
-	    <entry><structfield>input</structfield></entry>
+	    <entry><structfield>reserved2</structfield></entry>
 	    <entry></entry>
-	    <entry>Some video capture drivers support rapid and
-synchronous video input changes, a function useful for example in
-video surveillance applications. For this purpose applications set the
-<constant>V4L2_BUF_FLAG_INPUT</constant> flag, and this field to the
-number of a video input as in &v4l2-input; field
-<structfield>index</structfield>.</entry>
+	    <entry>A place holder for future extensions and custom
+(driver defined) buffer types
+<constant>V4L2_BUF_TYPE_PRIVATE</constant> and higher. Applications
+should set this to 0.</entry>
 	  </row>
 	  <row>
 	    <entry>__u32</entry>
@@ -923,13 +921,6 @@
 ioctl is called.</entry>
 	  </row>
 	  <row>
-	    <entry><constant>V4L2_BUF_FLAG_INPUT</constant></entry>
-	    <entry>0x0200</entry>
-	    <entry>The <structfield>input</structfield> field is valid.
-Applications set or clear this flag before calling the
-<constant>VIDIOC_QBUF</constant> ioctl.</entry>
-	  </row>
-	  <row>
 	    <entry><constant>V4L2_BUF_FLAG_PREPARED</constant></entry>
 	    <entry>0x0400</entry>
 	    <entry>The buffer has been prepared for I/O and can be queued by the