[media] v4l: add V4L2_PIX_FMT_Y12 format

Y12 is a grey-scale format with a depth of 12 bits per pixel stored in
16-bit words.

Signed-off-by: Michael Jones <michael.jones@matrix-vision.de>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/Documentation/DocBook/media-entities.tmpl b/Documentation/DocBook/media-entities.tmpl
index 5d259c6..fea63b4 100644
--- a/Documentation/DocBook/media-entities.tmpl
+++ b/Documentation/DocBook/media-entities.tmpl
@@ -294,6 +294,7 @@
 <!ENTITY sub-srggb10 SYSTEM "v4l/pixfmt-srggb10.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">
 <!ENTITY sub-pixfmt SYSTEM "v4l/pixfmt.xml">
 <!ENTITY sub-cropcap SYSTEM "v4l/vidioc-cropcap.xml">
 <!ENTITY sub-dbg-g-register SYSTEM "v4l/vidioc-dbg-g-register.xml">