Clang compile errors with psci_target_cpus on kria board

[midnightveil]

@cazb2 noticed that the board declaration for the kria doesn't work right, and it creates an unused psci_target_cpus warning which errors on his version of LLVM, as it picks up the zcu102 platform.

Not sure whether this is a false warning on something wrong, need to dig deeper.

    BoardInfo(
        name="kria_k26",
        arch=KernelArch.AARCH64,
        gcc_cpu="cortex-a53",
        loader_link_address=0x40000000,
        kernel_options={
            "KernelPlatform": "zynqmp",
            "KernelARMPlatform": "zcu102",
            "KernelCustomDTSOverlay": Path("custom_dts/overlay-zynqmp-kria-k26.dts"),
        },
    ),