rtc: mediatek: update MAINTAINERS entry with MediaTek RTC driver

I work for MediaTek on maintaining the MediaTek SoC based RTC driver for
the existing SoCs and keep adding support for the following SoCs in the
future.

Cc: Eddie Huang <eddie.huang@mediatek.com>
Signed-off-by: NSean Wang <sean.wang@mediatek.com>
Signed-off-by: NAlexandre Belloni <alexandre.belloni@free-electrons.com>

MAINTAINERS

@@ -1579,10 +1579,13 @@ F:	drivers/rtc/rtc-armada38x.c
 
 ARM/Mediatek RTC DRIVER
 M:	Eddie Huang <eddie.huang@mediatek.com>
+M:	Sean Wang <sean.wang@mediatek.com>
 L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
 L:	linux-mediatek@lists.infradead.org (moderated for non-subscribers)
 S:	Maintained
+F:	Documentation/devicetree/bindings/rtc/rtc-mt7622.txt
 F:	drivers/rtc/rtc-mt6397.c
+F:	drivers/rtc/rtc-mt7622.c
 
 ARM/Mediatek SoC support
 M:	Matthias Brugger <matthias.bgg@gmail.com>