dt-bindings: PCI: rcar-pci-host: Add optional regulators

Support regulators found on the KingFisher board for miniPCIe (1.5 and
3.3v). For completeness, describe a 12v regulator while we are here.

Link: https://lore.kernel.org/linux-pci/20231105092908.3792-2-wsa+renesas@sang-engineering.comSigned-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

Documentation/devicetree/bindings/pci/rcar-pci-host.yaml

@@ -68,6 +68,15 @@ properties:
   phy-names:
     const: pcie
 
+  vpcie1v5-supply:
+    description: The 1.5v regulator to use for PCIe.
+
+  vpcie3v3-supply:
+    description: The 3.3v regulator to use for PCIe.
+
+  vpcie12v-supply:
+    description: The 12v regulator to use for PCIe.
+
 required:
   - compatible
   - reg
@@ -121,5 +130,7 @@ examples:
              clock-names = "pcie", "pcie_bus";
              power-domains = <&sysc R8A7791_PD_ALWAYS_ON>;
              resets = <&cpg 319>;
+             vpcie3v3-supply = <&pcie_3v3>;
+             vpcie12v-supply = <&pcie_12v>;
          };
     };