Fix pci_unmap_addr() et al on i386.

We can run a 32-bit kernel on boxes with an IOMMU, so we need
pci_unmap_addr() etc. to work -- without it, drivers will leak mappings.

To be honest, this whole thing looks like it's more pain than it's
worth; I'm half inclined to remove the no-op #else case altogether.

But this is the minimal fix, which just does the right thing if
CONFIG_DMAR is set.

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Cc: stable@kernel.org  [ for 2.6.30 ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>