MAINTAINERS: update files of MediaTek USB3 PHYs

Update maintained files include MediaTek USB3 PHYs drivers and
their bindings

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>

MAINTAINERS

@@ -1647,7 +1647,8 @@ M:	Chunfeng Yun <chunfeng.yun@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:	drivers/phy/mediatek/phy-mtk-tphy.c
+F:	drivers/phy/mediatek/
+F:	Documentation/devicetree/bindings/phy/phy-mtk-*
 
 ARM/MICREL KS8695 ARCHITECTURE
 M:	Greg Ungerer <gerg@uclinux.org>