MAINTAINERS: Extend ARM/Mediatek SoC support section

Catch mt7623 and arm64 dts subdirectory.
Signed-off-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>
Signed-off-by: Olof Johansson <olof@lixom.net>

MAINTAINERS

@@ -1522,8 +1522,10 @@ L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
 L:	linux-mediatek@lists.infradead.org (moderated for non-subscribers)
 S:	Maintained
 F:	arch/arm/boot/dts/mt6*
+F:	arch/arm/boot/dts/mt7*
 F:	arch/arm/boot/dts/mt8*
 F:	arch/arm/mach-mediatek/
+F:	arch/arm64/boot/dts/mediatek/
 N:	mtk
 K:	mediatek