PCI: X86: Introduce and enable PCI domain support

* fix bug in pci_read() and pci_write() which prevented PCI domain
  support from working (hardcoded domain 0).

* unconditionally enable CONFIG_PCI_DOMAINS

* implement pci_domain_nr() and pci_proc_domain(), as required of
  all arches when CONFIG_PCI_DOMAINS is enabled.

* store domain in struct pci_sysdata, as assigned by ACPI

* support "pci=nodomains"

Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/arch/i386/Kconfig b/arch/i386/Kconfig
index 2d85e4b..515abb9 100644
--- a/arch/i386/Kconfig
+++ b/arch/i386/Kconfig
@@ -1137,6 +1137,11 @@
 	depends on PCI && ACPI && (PCI_GOMMCONFIG || PCI_GOANY)
 	default y
 
+config PCI_DOMAINS
+	bool
+	depends on PCI
+	default y
+
 source "drivers/pci/pcie/Kconfig"
 
 source "drivers/pci/Kconfig"