mx6: Add support for the mx6solox variant

mx6solox is the newest member of the mx6 family.

Some of the new features on this variants are:
- Cortex M4 microcontroller (besides the CortexA9)
- Dual Gigabit Ethernet

Add the initial support for it.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
diff --git a/arch/arm/include/asm/arch-mx6/mx6-ddr.h b/arch/arm/include/asm/arch-mx6/mx6-ddr.h
index d544d2e..5ebabfa 100644
--- a/arch/arm/include/asm/arch-mx6/mx6-ddr.h
+++ b/arch/arm/include/asm/arch-mx6/mx6-ddr.h
@@ -13,7 +13,11 @@
 #if defined(CONFIG_MX6DL) || defined(CONFIG_MX6S)
 #include "mx6dl-ddr.h"
 #else
+#ifdef CONFIG_MX6SX
+#include "mx6sx-ddr.h"
+#else
 #error "Please select cpu"
+#endif	/* CONFIG_MX6SX */
 #endif	/* CONFIG_MX6DL or CONFIG_MX6S */
 #endif	/* CONFIG_MX6Q */
 #else