Fix clash between IH_ARCH_NDS32 and IH_ARCH_SANDBOX

NDS32 and SANDBOX architecture were sharing the same IH_ARCH number
Signed-off-by: NStefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Acked-by: NMacpaul Lin <macpaul@andestech.com>
Acked-by: NMarek Vasut <marek.vasut@gmail.com>

include/image.h

@@ -107,7 +107,7 @@
 #define IH_ARCH_AVR32		17	/* AVR32	*/
 #define IH_ARCH_ST200	        18	/* STMicroelectronics ST200  */
 #define IH_ARCH_SANDBOX		19	/* Sandbox architecture (test only) */
-#define IH_ARCH_NDS32	        19	/* ANDES Technology - NDS32  */
+#define IH_ARCH_NDS32	        20	/* ANDES Technology - NDS32  */
 
 /*
  * Image Types