PCI: rcar: Add device tree support for r8a7743/5

Add internal PCI bridge support for r8a7743/5 SoC.  The Renesas RZ/G1[ME]
(R8A7743/5) internal PCI bridge is identical to the R-Car Gen2 family.

This doesn't change the driver, so it does nothing by itself.  But it does
mean that checkpatch won't complain about a future patch that adds
"renesas,pci-r8a7743" to a DT, which helps ensure that shipped DTs use
documented compatibility strings.
Signed-off-by: Biju Das <biju.das@bp.renesas.com>
[bhelgaas: add explanatory note]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Simon Horman <horms+renesas@verge.net.au>

Documentation/devicetree/bindings/pci/pci-rcar-gen2.txt

@@ -6,11 +6,14 @@ AHB. There is one bridge instance per USB port connected to the internal
 OHCI and EHCI controllers.
 
 Required properties:
-- compatible: "renesas,pci-r8a7790" for the R8A7790 SoC;
+- compatible: "renesas,pci-r8a7743" for the R8A7743 SoC;
+	      "renesas,pci-r8a7745" for the R8A7745 SoC;
+	      "renesas,pci-r8a7790" for the R8A7790 SoC;
 	      "renesas,pci-r8a7791" for the R8A7791 SoC;
 	      "renesas,pci-r8a7793" for the R8A7793 SoC;
 	      "renesas,pci-r8a7794" for the R8A7794 SoC;
-	      "renesas,pci-rcar-gen2" for a generic R-Car Gen2 compatible device
+	      "renesas,pci-rcar-gen2" for a generic R-Car Gen2 or
+				      RZ/G1 compatible device.
 
 
 	      When compatible with the generic version, nodes must list the