tools arch: Sync arch/x86/lib/memcpy_64.S with the kernel

Just a minor fix done in:

  Fixes: 26a37ab3 ("x86/mce: Fix copy/paste error in exception table entries")

Cc: Tony Luck <tony.luck@intel.com>
Link: http://lkml.kernel.org/n/tip-ni9jzdd5yxlail6pq8cuexw2@git.kernel.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>