checkpatch warnings with PCI DT compatible string

[Jiaxun Yang <jiaxun.yang@flygoat.com>]

Hi there,

When I was trying to create dts for my platform that need PCI
DeviceTree sub node to express interrupt of children devices under the
bridge, like this:

pci@1a000000 {
    compatible = "loongson,ls7a-pci";
    device_type = "pci";
    #address-cells = <3>;
    #size-cells = <2>;
    #interrupt-cells = <2>;
    msi-parent = <&msi>;

    reg = <0 0x1a000000 0 0x02000000>,
        <0xefe 0x00000000 0 0x20000000>;

    ranges = <0x01000000 0x0 0x00020000 0x0 0x00020000 0x0 0x00020000>,
            <0x02000000 0x0 0x40000000 0x0 0x40000000 0x0 0x40000000>;

    ohci@4,0 {
        compatible = "pci0014,7a24.0",
                    "pci0014,7a24",
                    "pciclass0c0310",
                    "pciclass0c03";

        reg = <0x2000 0x0 0x0 0x0 0x0>;
        interrupts = <49 IRQ_TYPE_LEVEL_HIGH>;
        interrupt-parent = <&pic>;
    };
};

I got such checkpatch warnings:

WARNING: DT compatible string "pci0014,7a24.0" appears un-documented --
check ./Documentation/devicetree/bindings/ #206: FILE:
arch/mips/boot/dts/loongson/ls7a-pch.dtsi:38:
+                               compatible = "pci0014,7a24.0",

WARNING: DT compatible string vendor "pci0014" appears un-documented --
check ./Documentation/devicetree/bindings/vendor-prefixes.yaml #206:
FILE: arch/mips/boot/dts/loongson/ls7a-pch.dtsi:38:
+                               compatible = "pci0014,7a24.0",

Just wonder if using such compatible string is allowed?

I've saw some some usages like mine in the tree, such as
arch/x86/platform/ce4100/falconfalls.dts, and
arch/mips/boot/dts/img/boston.dts.

If that's allowed, should we surpress these warnings in checkpatch
script?

Thanks.

--
Jiaxun Yang