mkelfimage: Add EM_AARCH64 as elf image type for arm64

Change-Id: I5510a4fe5085430b767161133113578b7cffa237
Signed-off-by: Furquan Shaikh <furquan@google.com>
Reviewed-on: https://chromium-review.googlesource.com/214327
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: Furquan Shaikh <furquan@chromium.org>
Commit-Queue: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/6954
Reviewed-by: Aaron Durbin <adurbin@google.com>
Tested-by: build bot (Jenkins)

util/mkelfImage/include/elf.h

@@ -91,6 +91,8 @@
 #define EM_XTENSA	94		/* Tensilica Xtensa Architecture */
 #define EM_NUM		95
 
+#define EM_AARCH64	183		/* ARM Aarch64 Architecture */
+
 /* Values for p_type. */
 #define PT_NULL		0	/* Unused entry. */
 #define PT_LOAD		1	/* Loadable segment. */