DT: pci: rcar-pci: document R8A77980 bindings

Document the R-Car V3H (R8A77980) SoC in the R-Car PCIe bindings.
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Reviewed-by: Rob Herring <robh@kernel.org>

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

@@ -8,6 +8,7 @@ compatible: "renesas,pcie-r8a7743" for the R8A7743 SoC;
 	    "renesas,pcie-r8a7793" for the R8A7793 SoC;
 	    "renesas,pcie-r8a7795" for the R8A7795 SoC;
 	    "renesas,pcie-r8a7796" for the R8A7796 SoC;
+	    "renesas,pcie-r8a77980" for the R8A77980 SoC;
 	    "renesas,pcie-rcar-gen2" for a generic R-Car Gen2 or
 				     RZ/G1 compatible device.
 	    "renesas,pcie-rcar-gen3" for a generic R-Car Gen3 compatible device.