ARM: mediatek: use more generic prompts for SoCs with ARMv7

Supported MediaTek SoCs with ARMv7 are not limited within MT65xx or MT81xx
and thus use more generic words to prompt users as the other vendors
usually use.
Signed-off-by: NSean Wang <sean.wang@mediatek.com>
Signed-off-by: NMatthias Brugger <matthias.bgg@gmail.com>

arch/arm/mach-mediatek/Kconfig

 menuconfig ARCH_MEDIATEK
-	bool "Mediatek MT65xx & MT81xx SoC"
+	bool "MediaTek SoC Support"
 	depends on ARCH_MULTI_V7
 	select ARM_GIC
 	select PINCTRL