dt-bindings: PCI: rcar-pci-host: Document missing R-Car H1 support

scripts/checkpatch.pl -f drivers/pci/controller/pcie-rcar-host.c:

    WARNING: DT compatible string "renesas,pcie-r8a7779" appears un-documented -- check ./Documentation/devicetree/bindings/
    #853: FILE: drivers/pci/controller/pcie-rcar-host.c:853:
    +	{ .compatible = "renesas,pcie-r8a7779",

Re-add the compatible value for R-Car H1, which was lost during the
json-schema conversion.  Make the "resets" property optional on R-Car
H1, as it is not present yet on R-Car Gen1 SoCs.

Fixes: 0d69ce3c

 ("dt-bindings: PCI: rcar-pci-host: Convert bindings to json-schema")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/fb0bb969cd0e5872ab5eac70e070242c0d8a5b81.1619700202.git.geert+renesas@glider.be
Signed-off-by: Rob Herring <robh@kernel.org>