mips: add initial support for qca956x referenced board

QCA9563 is CPU used on AP152 board :

    Clock speed : 750 MHz ,
    Arch :  Mips 74Kc,
    Eth : SGMII interface,
    MIMO config : 3 * 3 450M,
    2 * USB 2.0,

Signed-off-by: Rosy Song <rosysong@rosinson.com>

Changes for v2:
   - coding style cleanup
   - remove ununsed flash chip in defconfig
   - enable automatic icache / dcache size in defconfig

Changes for v3:
   - add detailed information for qca956x in commit message

Changes for v4:
   - remove pre-configured network settings in ap152.h

Changes for v5:
   - coding style cleanup
diff --git a/arch/mips/mach-ath79/Kconfig b/arch/mips/mach-ath79/Kconfig
index bc86f59..bdb23b5 100644
--- a/arch/mips/mach-ath79/Kconfig
+++ b/arch/mips/mach-ath79/Kconfig
@@ -33,6 +33,15 @@
 	help
 	  This supports QCA/Atheros qca953x family SOCs.
 
+config SOC_QCA956X
+	bool
+	select MIPS_TUNE_74KC
+	select SUPPORTS_BIG_ENDIAN
+	select SUPPORTS_CPU_MIPS32_R1
+	select SUPPORTS_CPU_MIPS32_R2
+	help
+	  This supports QCA/Atheros qca956x family SOCs.
+
 choice
 	prompt "Board select"
 
@@ -44,6 +53,10 @@
 	bool "AP143 Reference Board"
 	select SOC_QCA953X
 
+config TARGET_AP152
+	bool "AP152 Reference Board"
+	select SOC_QCA956X
+
 config BOARD_TPLINK_WDR4300
 	bool "TP-Link WDR4300 Board"
 	select SOC_AR934X
@@ -52,6 +65,7 @@
 
 source "board/qca/ap121/Kconfig"
 source "board/qca/ap143/Kconfig"
+source "board/qca/ap152/Kconfig"
 source "board/tplink/wdr4300/Kconfig"
 
 endmenu