[media] add V4L2-PIX-FMT-SRGGB12 & friends to docbook

The xml with those guys are there, but they weren't included
on the docbook.
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

Documentation/DocBook/media-entities.tmpl

@@ -293,6 +293,7 @@
 <!ENTITY sub-yuyv SYSTEM "v4l/pixfmt-yuyv.xml">
 <!ENTITY sub-yvyu SYSTEM "v4l/pixfmt-yvyu.xml">
 <!ENTITY sub-srggb10 SYSTEM "v4l/pixfmt-srggb10.xml">
+<!ENTITY sub-srggb12 SYSTEM "v4l/pixfmt-srggb12.xml">
 <!ENTITY sub-srggb8 SYSTEM "v4l/pixfmt-srggb8.xml">
 <!ENTITY sub-y10 SYSTEM "v4l/pixfmt-y10.xml">
 <!ENTITY sub-y12 SYSTEM "v4l/pixfmt-y12.xml">

Documentation/DocBook/v4l/pixfmt.xml

@@ -673,6 +673,7 @@ access the palette, this must be done with ioctls of the Linux framebuffer API.<
     &sub-srggb8;
     &sub-sbggr16;
     &sub-srggb10;
+    &sub-srggb12;
   </section>
 
   <section id="yuv-formats">