[media] V4L2 Spec: fix typo: NTSC -> NRSC

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

Documentation/DocBook/media/v4l/biblio.xml

@@ -194,7 +194,7 @@ in the frequency range from 87,5 to 108,0 MHz</title>
 	<corpauthor>National Radio Systems Committee
 (<ulink url="http://www.nrscstandards.org">http://www.nrscstandards.org</ulink>)</corpauthor>
       </authorgroup>
-      <title>NTSC-4: United States RBDS Standard</title>
+      <title>NRSC-4: United States RBDS Standard</title>
     </biblioentry>
 
     <biblioentry id="iso12232">