[media] v4l: Documentation for the NV12MT format

Added documentation for V4L2_PIX_FMT_NV12MT format. This is a YUV 4:2:0
format with macro block size of 64x32 and specific order of macro blocks
in the memory.

Signed-off-by: Kamil Debski <k.debski@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.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 40158ee..5d259c6 100644
--- a/Documentation/DocBook/media-entities.tmpl
+++ b/Documentation/DocBook/media-entities.tmpl
@@ -272,6 +272,7 @@
 <!ENTITY sub-grey SYSTEM "v4l/pixfmt-grey.xml">
 <!ENTITY sub-nv12 SYSTEM "v4l/pixfmt-nv12.xml">
 <!ENTITY sub-nv12m SYSTEM "v4l/pixfmt-nv12m.xml">
+<!ENTITY sub-nv12mt SYSTEM "v4l/pixfmt-nv12mt.xml">
 <!ENTITY sub-nv16 SYSTEM "v4l/pixfmt-nv16.xml">
 <!ENTITY sub-packed-rgb SYSTEM "v4l/pixfmt-packed-rgb.xml">
 <!ENTITY sub-packed-yuv SYSTEM "v4l/pixfmt-packed-yuv.xml">