PCI: iproc: Add PAXBv2 binding info

Add new compatible string 'brcm,iproc-pcie-paxb-v2', for the next
generation of the iProc PAXB PCIe host controller.
Signed-off-by: NOza Oza <oza.oza@broadcom.com>
Signed-off-by: NRay Jui <ray.jui@broadcom.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: NScott Branden <scott.branden@broadcom.com>

Documentation/devicetree/bindings/pci/brcm,iproc-pcie.txt

@@ -4,6 +4,8 @@ Required properties:
 - compatible:
       "brcm,iproc-pcie" for the first generation of PAXB based controller,
 used in SoCs including NSP, Cygnus, NS2, and Pegasus
+      "brcm,iproc-pcie-paxb-v2" for the second generation of PAXB-based
+controllers, used in Stingray
       "brcm,iproc-pcie-paxc" for the first generation of PAXC based
 controller, used in NS2
       "brcm,iproc-pcie-paxc-v2" for the second generation of PAXC based