aspeed: Add AST2600 platform support

Add low level platform initialization for the AST2600 SoC.
The 2-stage booting with U-Boot SPL are leveraged to support
different booting mode.

However, currently the patch supports only the booting from
memory-mapped SPI flash.

Signed-off-by: Chia-Wei, Wang <chiawei_wang@aspeedtech.com>
Reviewed-by: Ryan Chen <ryan_chen@aspeedtech.com>
diff --git a/arch/arm/mach-aspeed/ast2600/Kconfig b/arch/arm/mach-aspeed/ast2600/Kconfig
new file mode 100644
index 0000000..f3a5338
--- /dev/null
+++ b/arch/arm/mach-aspeed/ast2600/Kconfig
@@ -0,0 +1,17 @@
+if ASPEED_AST2600
+
+config SYS_CPU
+	default "armv7"
+
+config TARGET_EVB_AST2600
+	bool "EVB-AST2600"
+	depends on ASPEED_AST2600
+	help
+	  EVB-AST2600 is Aspeed evaluation board for AST2600A0 chip.
+	  It has 512M of RAM, 32M of SPI flash, two Ethernet ports,
+	  4 Serial ports, 4 USB ports, VGA port, PCIe, SD card slot,
+	  20 pin JTAG, pinouts for 14 I2Cs, 3 SPIs and eSPI, 8 PWMs.
+
+source "board/aspeed/evb_ast2600/Kconfig"
+
+endif