Required properties:
- compatible: "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