MAINTAINERS: use the correct location for dt-bindings includes for mux

Just drop the "linux" part of the path, it was never correct.

Reported-by: Joe Perches <joe@perches.com>
Fixes: 256ac03750 ("dt-bindings: document devicetree bindings for mux-controllers and gpio-mux")
Signed-off-by: Peter Rosin <peda@axentia.se>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

MAINTAINERS

@@ -9865,7 +9865,7 @@ M:	Peter Rosin <peda@axentia.se>
 S:	Maintained
 F:	Documentation/ABI/testing/sysfs-class-mux*
 F:	Documentation/devicetree/bindings/mux/
-F:	include/linux/dt-bindings/mux/
+F:	include/dt-bindings/mux/
 F:	include/linux/mux/
 F:	drivers/mux/