mips: add base support for QCA/Atheros ath79 SOCs

This patch add some common code for QCA/Atheros ath79 SOCs such as
DDR tuning, chip reset and CPU detection.

Signed-off-by: Wills Wang <wills.wang@live.com>
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index fe37d1f..7162f3c 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -55,6 +55,11 @@
 	select SYS_MIPS_CACHE_INIT_RAM_LOAD
 	select MIPS_TUNE_4KC
 
+config ARCH_ATH79
+	bool "Support QCA/Atheros ath79"
+	select OF_CONTROL
+	select DM
+
 config MACH_PIC32
 	bool "Support Microchip PIC32"
 	select OF_CONTROL
@@ -67,6 +72,7 @@
 source "board/micronas/vct/Kconfig"
 source "board/pb1x00/Kconfig"
 source "board/qemu-mips/Kconfig"
+source "arch/mips/mach-ath79/Kconfig"
 source "arch/mips/mach-pic32/Kconfig"
 
 if MIPS