MAINTAINERS: add MT7621 CLOCK maintainer

Adding myself as maintainer for mt7621 clock driver.
Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Link: https://lore.kernel.org/r/20210410055059.13518-5-sergio.paracuellos@gmail.comSigned-off-by: Stephen Boyd <sboyd@kernel.org>

MAINTAINERS

@@ -11295,6 +11295,12 @@ L:	linux-wireless@vger.kernel.org
 S:	Maintained
 F:	drivers/net/wireless/mediatek/mt7601u/
 
+MEDIATEK MT7621 CLOCK DRIVER
+M:	Sergio Paracuellos <sergio.paracuellos@gmail.com>
+S:	Maintained
+F:	Documentation/devicetree/bindings/clock/mediatek,mt7621-sysc.yaml
+F:	drivers/clk/ralink/clk-mt7621.c
+
 MEDIATEK MT7621/28/88 I2C DRIVER
 M:	Stefan Roese <sr@denx.de>
 L:	linux-i2c@vger.kernel.org