mips: rename mach-mt7620 to mach-mtmips

Currently mach-mt7620 contains only support for mt7628. To avoid confusion,
rename mach-mt7620 to mach-mtmips, which means MediaTek MIPS platforms.
MT7620 and MT7628 should be distinguished by SOC_MT7620 and SOC_MT7628
because they do not share the same lowlevel codes.

Dependencies of four drivers are changed to SOC_MT7628 as these drivers
are only used by MT7628.

Cc: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Reviewed-by: Stefan Roese <sr@denx.de>
Signed-off-by: Weijie Gao <weijie.gao@mediatek.com>
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 194f4f3..9cf8e98 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -74,8 +74,8 @@
 	select SYSRESET
 	imply CMD_DM
 
-config ARCH_MT7620
-	bool "Support MT7620/7688 SoCs"
+config ARCH_MTMIPS
+	bool "Support MediaTek MIPS platforms"
 	imply CMD_DM
 	select DISPLAY_CPUINFO
 	select DM
@@ -153,7 +153,7 @@
 source "arch/mips/mach-bmips/Kconfig"
 source "arch/mips/mach-jz47xx/Kconfig"
 source "arch/mips/mach-pic32/Kconfig"
-source "arch/mips/mach-mt7620/Kconfig"
+source "arch/mips/mach-mtmips/Kconfig"
 
 if MIPS