MAINTAINERS: Add keyword match for of_match_table to device tree section

If a patch is working with an of_match_table it's probably adding an OF
binding to a driver in which case the binding ought to be reviewed by the
device tree folks to make sure that things like the device matches are set
up correctly.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

MAINTAINERS

@@ -4722,6 +4722,7 @@ S:	Maintained
 F:	drivers/of
 F:	include/linux/of*.h
 K:	of_get_property
+K:	of_match_table
 
 OPENRISC ARCHITECTURE
 M:	Jonas Bonn <jonas@southpole.se>