PCI: xgene: Add APM X-Gene PCIe driver

Add the AppliedMicro X-Gene SOC PCIe host controller driver.  The X-Gene
PCIe controller supports up to 8 lanes and GEN3 speed.  The X-Gene SOC
supports up to 5 PCIe ports.

[bhelgaas: folded in MAINTAINERS and bindings updates]
Tested-by: Ming Lei <ming.lei@canonical.com>
Tested-by: Dann Frazier <dann.frazier@canonical.com>
Signed-off-by: Tanmay Inamdar <tinamdar@apm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Liviu Dudau <Liviu.Dudau@arm.com> (driver)
diff --git a/MAINTAINERS b/MAINTAINERS
index 1ff06de..076eb68 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -6868,6 +6868,14 @@
 F:	arch/x86/pci/
 F:	arch/x86/kernel/quirks.c
 
+PCI DRIVER FOR APPLIEDMICRO XGENE
+M:	Tanmay Inamdar <tinamdar@apm.com>
+L:	linux-pci@vger.kernel.org
+L:	linux-arm-kernel@lists.infradead.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/pci/xgene-pci.txt
+F:	drivers/pci/host/pci-xgene.c
+
 PCI DRIVER FOR IMX6
 M:	Richard Zhu <r65037@freescale.com>
 M:	Shawn Guo <shawn.guo@freescale.com>