gpu: nova-core: provide a clear error report for unsupported GPUs

gpu: nova-core: provide a clear error report for unsupported GPUs

Pass in a PCI device to Spec::new(), and provide a Display
implementation for boot42, in order to provide a clear, concise report
of what happened: the driver read NV_PMC_BOOT42, and found that the GPU
is not supported.

For very old GPUs (older than Fermi), the driver still returns ENODEV,
but it does so without a driver-specific dmesg report. That is exactly
appropriate, because if such a GPU is installed, it can only be
supported by Nouveau. And if so, the user is not helped by additional
error messages from Nova.

Here's the full dmesg output for a Blackwell (not yet supported) GPU:

NovaCore 0000:01:00.0: Probe Nova Core GPU driver.
NovaCore 0000:01:00.0: Unsupported chipset: boot42 = 0x1b2a1000 (architecture 0x1b, implementation 0x2)
NovaCore 0000:01:00.0: probe with driver NovaCore failed with error -524

Cc: Alexandre Courbot <acourbot@nvidia.com>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Timur Tabi <ttabi@nvidia.com>
Cc: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
[acourbot@nvidia.com: fix commit log with ENODEV (not ENOTSUPP) error
code for unsupported GPUs.]
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Message-ID: <20251115010923.1192144-5-jhubbard@nvidia.com>