ieee802154: Add entry in MAINTAINTERS for MCR20a driver

Signed-off-by: Xue Liu <[e-mail]>
Signed-off-by: Stefan Schmidt <[e-mail]>

MAINTAINERS

···
 F:	Documentation/ABI/testing/sysfs-bus-iio-potentiometer-mcp4531
 F:	drivers/iio/potentiometer/mcp4531.c
 
+MCR20A IEEE-802.15.4 RADIO DRIVER
+M:	Xue Liu <[e-mail]>
+L:	[e-mail]
+W:	https://github.com/xueliu/mcr20a-linux
+S:	Maintained
+F:	drivers/net/ieee802154/mcr20a.c
+F:	drivers/net/ieee802154/mcr20a.h
+F:	Documentation/devicetree/bindings/net/ieee802154/mcr20a.txt
+
 MEASUREMENT COMPUTING CIO-DAC IIO DRIVER
 M:	William Breathitt Gray <[e-mail]>
 L:	[e-mail]