The following error occurs for the `make ARCH=arm64 checkstack` case:
aarch64-linux-gnu-objdump -d vmlinux $(find . -name '*.ko') | \
perl ./scripts/checkstack.pl arm64
wrong or unknown architecture "arm64"
As suggested by Masahiro Yamada, fix the above error using regular
expressions in the same way it was fixed for the `ARCH=x86` case via
commit 
fda9f9903be6 ("scripts/checkstack.pl: automatically handle
32-bit and 64-bit mode for ARCH=x86").
Suggested-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: George G. Davis <george_davis@mentor.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
 
        $x      = "[0-9a-f]";   # hex character
        $xs     = "[0-9a-f ]";  # hex character or space
        $funcre = qr/^$x* <(.*)>:$/;
-       if ($arch eq 'aarch64') {
+       if ($arch =~ '^(aarch|arm)64$') {
                #ffffffc0006325cc:       a9bb7bfd        stp     x29, x30, [sp, #-80]!
                #a110:       d11643ff        sub     sp, sp, #0x590
                $re = qr/^.*stp.*sp, \#-([0-9]{1,8})\]\!/o;