arm64: core support

Relocation code based on a patch by Scott Wood, which is:
Signed-off-by: Scott Wood <scottwood@freescale.com>

Signed-off-by: David Feng <fenghua@phytium.com.cn>
diff --git a/common/image.c b/common/image.c
index b0ae58f..4145354 100644
--- a/common/image.c
+++ b/common/image.c
@@ -81,6 +81,7 @@
 	{	IH_ARCH_NDS32,		"nds32",	"NDS32",	},
 	{	IH_ARCH_OPENRISC,	"or1k",		"OpenRISC 1000",},
 	{	IH_ARCH_SANDBOX,	"sandbox",	"Sandbox",	},
+	{	IH_ARCH_ARM64,		"arm64",	"AArch64",	},
 	{	-1,			"",		"",		},
 };