MAINTAINERS: Add file patterns for ata 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>
Cc: Tejun Heo <tj@kernel.org>
Cc: linux-ide@vger.kernel.org
Signed-off-by: Tejun Heo <tj@kernel.org>

MAINTAINERS

@@ -6732,6 +6732,7 @@ S:	Maintained
 F:	drivers/ata/
 F:	include/linux/ata.h
 F:	include/linux/libata.h
+F:	Documentation/devicetree/bindings/ata/
 
 LIBATA PATA ARASAN COMPACT FLASH CONTROLLER
 M:	Viresh Kumar <vireshk@kernel.org>