imx: arch-mx6: add is_soc_type helper macro

Add helper macro is_soc_type to identify iMX SoC family

Signed-off-by: Adrian Alonso <aalonso@freescale.com>
diff --git a/arch/arm/include/asm/arch-imx/cpu.h b/arch/arm/include/asm/arch-imx/cpu.h
index 1c8d24e..416905a 100644
--- a/arch/arm/include/asm/arch-imx/cpu.h
+++ b/arch/arm/include/asm/arch-imx/cpu.h
@@ -23,6 +23,8 @@
 #define MXC_CPU_MX6QP		0x69
 #define MXC_CPU_VF610		0xF6 /* dummy ID */
 
+#define MXC_SOC_MX6		0x60
+
 #define CS0_128					0
 #define CS0_64M_CS1_64M				1
 #define CS0_64M_CS1_32M_CS2_32M			2