fdt_cpu_scaling unit test not working on ARM64

[tjones60]

When running the fdt_cpu_scaling unit test on Windows ARM64, it fails with the following error:

       ABORT [   0.100s] openhcl_boot::bin/openhcl_boot test::fdt_cpu_scaling
     Message [         ] code 0xc000001d: OS Error -1073741795 (FormatMessageW() returned error 317) (os error -1073741795)

When running on Linux ARM64, the test passes if the buffer size is increased, but this does not appear to be sufficient on Windows. In addition, there might also be something we can do here to improve the error message here; there seems to be something whole with printing OS errors.