swiotlb: add hwdev to swiotlb_phys_to_bus() / swiotlb_sg_to_bus()

Impact: extend functions with a (yet unused) parameter, update callsites

Some architectures need it - in preparation for highmem swiotlb.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>