It was disabled when x86_64 was introduced, but it is reported to be
working on 64bit by two different people, so let's enable it back
again.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: "Juergen E. Fischer" <fischer@norbit.de>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>