cbfstool: add aarch64 as a name

The aarch64 is not really an arm variant, it's sufficiently
different that it can be considered (for purposes of cbfs, certainly)
to be a new architecture.

Add a constant in cbfs.h and strings to correspond to it.
Note that with the new cbfstool support that we added earlier,
the actual use of aarch64 ELF files actually "just works" (at
least when tested earlier).

Change-Id: Ib4900900d99c9aae6eef858d8ee097709368c4d4
Reviewed-on: https://chromium-review.googlesource.com/180221
Reviewed-by: Stefan Reinauer <reinauer@chromium.org>
Commit-Queue: Ronald Minnich <rminnich@chromium.org>
Tested-by: Ronald Minnich <rminnich@chromium.org>
(cherry picked from commit f836e14695827b2667804bc1058e08ec7b297921)
Signed-off-by: Isaac Christensen <isaac.christensen@se-eng.com>
Reviewed-on: http://review.coreboot.org/6896
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
diff --git a/util/cbfstool/cbfs.h b/util/cbfstool/cbfs.h
index 6a54bc8..348a4da 100644
--- a/util/cbfstool/cbfs.h
+++ b/util/cbfstool/cbfs.h
@@ -52,6 +52,7 @@
 #define CBFS_ARCHITECTURE_UNKNOWN  0xFFFFFFFF
 #define CBFS_ARCHITECTURE_X86      0x00000001
 #define CBFS_ARCHITECTURE_ARM      0x00000010
+#define CBFS_ARCHITECTURE_AARCH64  0x0000aa64
 
 #define CBFS_FILE_MAGIC "LARCHIVE"