Claude review: gpu: nova-core: allocate PCI MSI vector during probe

[Claude Code Review Bot <claude-review@example.com>]

Patch Review

```rust
_: {
    let _irq_vector = irq::alloc_vector(pdev)?;
},
```

**Issue:** The allocated `_irq_vector` is immediately dropped via the `_` prefix. The `IrqVector` is presumably a devres-managed resource, but if the `IrqVector<'_>` carries any drop logic (e.g., freeing the vector), dropping it here would undo the allocation. Need to confirm that the PCI IRQ allocation is devres-managed independently of the `IrqVector` handle's lifetime.

**Issue:** In `alloc_vector`, the return type is `Result<pci::IrqVector<'_>>`:
```rust
Ok(*irq_vectors.start())
```
This dereferences the start of the range. If `IrqVector` is `Copy`, this is fine. If it isn't, this won't compile. Given that the patches were tested, it must be fine, but it's worth noting the implicit `Copy` requirement.

**Design question:** The INTx fallback path:
```rust
Err(_) => {
    dev_warn!(pdev.as_ref(), "MSI not available, falling back to INTx\n");
    pdev.alloc_irq_vectors(1, 1, IrqTypes::default().with(IrqType::Intx))?
}
```
INTx fallback for a GPU driver in 2026 is generous. Modern NVIDIA GPUs all support MSI. If INTx can't actually work with INTR_CTRL's edge-triggered MSI semantics (as documented in patch 7), should this just fail hard instead of silently degrading to a mode that may not function correctly?

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Generated by Claude Code Patch Reviewer