[media] DocBook/media/v4l: update VIDIOC_DBG_ documentation

- Remove the "On failure the structure remains unchanged." part since
that isn't necessarily true.
- Document the 'size' field.

Signed-off-by: Hans Verkuil <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

Documentation/DocBook/media/v4l/vidioc-dbg-g-chip-info.xml

···
 and call <constant>VIDIOC_DBG_G_CHIP_INFO</constant> with a pointer to
 this structure. On success the driver stores information about the
 selected chip in the <structfield>name</structfield> and
-<structfield>flags</structfield> fields. On failure the structure
-remains unchanged.</para>
+<structfield>flags</structfield> fields.</para>
 
     <para>When <structfield>match.type</structfield> is
 <constant>V4L2_CHIP_MATCH_BRIDGE</constant>,

Documentation/DocBook/media/v4l/vidioc-dbg-g-register.xml

···
 to enable these ioctls.</para>
 
     <para>To write a register applications must initialize all fields
-of a &v4l2-dbg-register; and call
+of a &v4l2-dbg-register; except for <structfield>size</structfield> and call
 <constant>VIDIOC_DBG_S_REGISTER</constant> with a pointer to this
 structure. The <structfield>match.type</structfield> and
 <structfield>match.addr</structfield> or <structfield>match.name</structfield>
···
 <structfield>reg</structfield> fields, and call
 <constant>VIDIOC_DBG_G_REGISTER</constant> with a pointer to this
 structure. On success the driver stores the register value in the
-<structfield>val</structfield> field. On failure the structure remains
-unchanged.</para>
+<structfield>val</structfield> field and the size (in bytes) of the
+value in <structfield>size</structfield>.</para>
 
     <para>When <structfield>match.type</structfield> is
 <constant>V4L2_CHIP_MATCH_BRIDGE</constant>,
···
 url="http://linuxtv.org/repo/">http://linuxtv.org/repo/</ulink> for
 access instructions.</para>
 
-    <!-- Note for convenience vidioc-dbg-g-chip-ident.sgml
+    <!-- Note for convenience vidioc-dbg-g-chip-info.sgml
 	 contains a duplicate of this table. -->
     <table pgwide="1" frame="none" id="v4l2-dbg-match">
       <title>struct <structname>v4l2_dbg_match</structname></title>
···
 	    <entry>How to match the chip, see <xref linkend="v4l2-dbg-match" />.</entry>
 	  </row>
 	  <row>
+	    <entry>__u32</entry>
+	    <entry><structfield>size</structfield></entry>
+	    <entry>The register size in bytes.</entry>
+	  </row>
+	  <row>
 	    <entry>__u64</entry>
 	    <entry><structfield>reg</structfield></entry>
 	    <entry>A register number.</entry>
···
       </tgroup>
     </table>
 
-    <!-- Note for convenience vidioc-dbg-g-chip-ident.sgml
+    <!-- Note for convenience vidioc-dbg-g-chip-info.sgml
 	 contains a duplicate of this table. -->
     <table pgwide="1" frame="none" id="chip-match-types">
       <title>Chip Match Types</title>