MAINTAINERS: update maintainer for MediaTek MIPS platform

Update maintainer for MediaTek MIPS platform

diff --git a/MAINTAINERS b/MAINTAINERS
index 1baa038..2047a2a 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1031,15 +1031,23 @@
 S:	Maintained
 F:	arch/mips/mach-mtmips/
 F:	arch/mips/dts/mt7620.dtsi
+F:	arch/mips/dts/mt7621.dtsi
 F:	arch/mips/dts/mt7620-u-boot.dtsi
+F:	arch/mips/dts/mt7621-u-boot.dtsi
 F:	include/configs/mt7620.h
+F:	include/configs/mt7621.h
 F:	include/dt-bindings/clock/mt7620-clk.h
+F:	include/dt-bindings/clock/mt7621-clk.h
 F:	include/dt-bindings/clock/mt7628-clk.h
 F:	include/dt-bindings/reset/mt7620-reset.h
+F:	include/dt-bindings/reset/mt7621-reset.h
 F:	include/dt-bindings/reset/mt7628-reset.h
 F:	drivers/clk/mtmips/
 F:	drivers/pinctrl/mtmips/
 F:	drivers/gpio/mt7620_gpio.c
+F:	drivers/mtd/nand/raw/mt7621_nand.c
+F:	drivers/mtd/nand/raw/mt7621_nand.h
+F:	drivers/mtd/nand/raw/mt7621_nand_spl.c
 F:	drivers/net/mt7620-eth.c
 F:	drivers/phy/mt7620-usb-phy.c
 F:	drivers/reset/reset-mtmips.c