[IA64] missing exports hwsw_sync_...

Add missing exports to allow several drivers to be built as module with
CONFIG_IA64_HP_ZX1_SWIOTLB.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>