intel-iommu: Handle PCI domains appropriately.

We were comparing {bus,devfn} and assuming that a match meant it was the
same device. It doesn't -- the same {bus,devfn} can exist in
multiple PCI domains. Include domain number in device identification
(and call it 'segment' in most places, because there's already a lot of
references to 'domain' which means something else, and this code is
infected with ACPI thinking already).

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

drivers/pci/dmar.c

@@ -180,6 +180,7 @@ dmar_parse_one_drhd(struct acpi_dmar_header *header)
 	dmaru->hdr = header;
 	drhd = (struct acpi_dmar_hardware_unit *)header;
 	dmaru->reg_base_addr = drhd->address;
+	dmaru->segment = drhd->segment;
 	dmaru->include_all = drhd->flags & 0x1; /* BIT0: INCLUDE_ALL */
 
 	ret = alloc_iommu(dmaru);