arm64: mediatek: cleanup message for platform selection

The latest kernel tree already can support more MediaTek platforms such as
MT2712 and MT7622, so additional descriptions for those platforms are added
and certain cleanups are also being made here.
Signed-off-by: NSean Wang <sean.wang@mediatek.com>
Signed-off-by: NMatthias Brugger <matthias.bgg@gmail.com>

arch/arm64/Kconfig.platforms

@@ -91,12 +91,13 @@ config ARCH_HISI
 	  This enables support for Hisilicon ARMv8 SoC family
 
 config ARCH_MEDIATEK
-	bool "Mediatek MT65xx & MT81xx ARMv8 SoC"
+	bool "MediaTek SoC Family"
 	select ARM_GIC
 	select PINCTRL
 	select MTK_TIMER
 	help
-	  Support for Mediatek MT65xx & MT81xx ARMv8 SoCs
+	  This enables support for MediaTek MT27xx, MT65xx, MT76xx
+	  & MT81xx ARMv8 SoCs
 
 config ARCH_MESON
 	bool "Amlogic Platforms"