MAINTAINERS: Add file patterns for pinctrl 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 <[email protected]>
Cc: Linus Walleij <[email protected]>
Cc: [email protected]
Signed-off-by: Linus Walleij <[email protected]>

Author: geertu

MAINTAINERS

@@ -8944,6 +8944,7 @@ M:	Linus Walleij <[email protected]>
 L:	[email protected]
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl.git
 S:	Maintained
+F:	Documentation/devicetree/bindings/pinctrl/
 F:	drivers/pinctrl/
 F:	include/linux/pinctrl/