arc: bdinfo, image and arc-specific init functions declarations support

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>

Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Francois Bedard <fbedard@synopsys.com>
Cc: Wolfgang Denk <wd@denx.de>
Cc: Heiko Schocher <hs@denx.de>
diff --git a/include/image.h b/include/image.h
index 7de2bb2..3ba8c2e 100644
--- a/include/image.h
+++ b/include/image.h
@@ -157,6 +157,7 @@
 #define IH_ARCH_NDS32	        20	/* ANDES Technology - NDS32  */
 #define IH_ARCH_OPENRISC        21	/* OpenRISC 1000  */
 #define IH_ARCH_ARM64		22	/* ARM64	*/
+#define IH_ARCH_ARC		23	/* Synopsys DesignWare ARC */
 
 /*
  * Image Types