Fix the field-id enum name in the nvml test helper supports_nvlink

[LeSingh1]

def supports_nvlink(device):
    fields = nvml.FieldValue(1)
    fields[0].field_id = nvml.FI.DEV_NVLINK_GET_STATE
    return nvml.device_get_field_values(device, fields)[0].nvml_return == nvml.Return.SUCCESS

There is no FI attribute on cuda.bindings.nvml. The enum is FieldId
(nvml.pyx:1229), with DEV_NVLINK_GET_STATE at nvml.pyx:1454. The sibling test uses
the correct spelling:

# tests/nvml/test_nvlink.py:19
        fields[0].field_id = nvml.FieldId.DEV_NVLINK_LINK_COUNT

So the helper raises AttributeError on its first line of real work.

Nobody has noticed because it has no callers — a repo-wide grep for supports_nvlink
finds only its own definition. Contrast util.supports_ecc in the same file, which is
called from test_page_retirement.py:35,61. This is a guard that cannot fire because it
is never invoked, and would crash if it were.

Why fix rather than delete

Deleting the dead helper is the other reasonable option, and I am happy to switch if you
prefer it. I went with the fix because supports_nvlink sits next to supports_ecc and
is_vgpu as part of an obviously intended capability-probe set, and because a test now
keeps it honest instead of letting it rot again.

Test

New cuda_bindings/tests/nvml/test_util.py. It stubs nvml.device_get_field_values, so
the helper runs without an NVLink-capable device, and asserts both that it returns True
and that it queried FieldId.DEV_NVLINK_GET_STATE. It fails on main with
AttributeError: module 'cuda.bindings.nvml' has no attribute 'FI'.

The test uses the package-relative from . import util that test_gpu.py and
test_page_retirement.py already use, and inherits the hardware_supports_nvml() gate in
tests/nvml/__init__.py.

ruff check and ruff format --check are clean.

[copy-pr-bot]

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