MAINTAINERS: Add file patterns for media device tree bindings

Submitters of device tree binding documentation may forget to CC
the subsystem maintainer if this is missing.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

MAINTAINERS

@@ -8075,6 +8075,7 @@ W:	https://linuxtv.org
 Q:	http://patchwork.kernel.org/project/linux-media/list/
 T:	git git://linuxtv.org/media_tree.git
 S:	Maintained
+F:	Documentation/devicetree/bindings/media/
 F:	Documentation/media/
 F:	drivers/media/
 F:	drivers/staging/media/