ARM64: PCI: Add acpi_pci_bus_find_domain_nr()

Extend pci_bus_find_domain_nr() so it can find the domain from either:

  - ACPI, via the new acpi_pci_bus_find_domain_nr() interface, or
  - DT, via of_pci_bus_find_domain_nr()

Note that this is only used for CONFIG_PCI_DOMAINS_GENERIC=y, so it does
not affect x86 or ia64.

[bhelgaas: changelog]
Signed-off-by: Tomasz Nowicki <tn@semihalf.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 97f7cd4..4834cee 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -7,6 +7,7 @@
  *	Copyright 1997 -- 2000 Martin Mares <mj@ucw.cz>
  */
 
+#include <linux/acpi.h>
 #include <linux/kernel.h>
 #include <linux/delay.h>
 #include <linux/init.h>
@@ -4990,7 +4991,8 @@
 
 int pci_bus_find_domain_nr(struct pci_bus *bus, struct device *parent)
 {
-	return of_pci_bus_find_domain_nr(parent);
+	return acpi_disabled ? of_pci_bus_find_domain_nr(parent) :
+			       acpi_pci_bus_find_domain_nr(bus);
 }
 #endif
 #endif