hysdn: No longer broken on SMP.

With the cli/sti code sorted out we think this driver is OK for use on
SMP systems.

Acked-by: Mark Asselstine <mark.asselstine@windriver.com>
Acked-by: Karsten Keil <kkeil@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>