MAINTAINERS: Add DT Bindings for Auxiliary Display Drivers

The "AUXILIARY DISPLAY DRIVERS" section lacks the related DT bindings.
Add them.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

Author: geertu

MAINTAINERS

@@ -3125,6 +3125,7 @@ F:	lib/*audit.c
 AUXILIARY DISPLAY DRIVERS
 M:	Miguel Ojeda <ojeda@kernel.org>
 S:	Maintained
+F:	Documentation/devicetree/bindings/auxdisplay/
 F:	drivers/auxdisplay/
 F:	include/linux/cfag12864b.h