Claude review: vgaarb: pass errors from pci_set_vga_state up

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

Patch Review

This patch converts `__vga_tryget` to propagate `pci_set_vga_state` errors via `ERR_PTR`, and updates `vga_get` to handle the new error pointer returns.

> +		err = pci_set_vga_state(conflict->pdev, false, pci_bits, flags);
> +		if (unlikely(err))
> +			return ERR_PTR(err);
>  		conflict->owns &= ~match;

When `pci_set_vga_state(conflict->pdev, false, ...)` fails, the function returns immediately. At this point, VGA state for the *requesting* device has not been enabled yet, and the conflict device's `owns` bits have not been updated, so the data structures remain consistent. However, if this is not the first iteration of the `list_for_each_entry` loop, earlier iterations may have already successfully disabled VGA on other conflicting devices (via `pci_set_vga_state(false)`) and cleared their `owns` bits. Those devices have lost VGA ownership in the software state and in hardware, but the requesting device never got it. This leaves the system in a state where nobody owns VGA. Is this an acceptable outcome, or should the series attempt to roll back the changes to previously-processed conflicts?

> +		if (IS_ERR(conflict))
> +		{
> +			rc = PTR_ERR(conflict);
> +			break;
> +		}

Same brace style issue. The `IS_ERR` check in `vga_get` is correct.

However, `vga_tryget()` also calls `__vga_tryget` and is **not updated** by this patch:

```c
if (__vga_tryget(vgadev, rsrc))
    rc = -EBUSY;
```

After this patch, `__vga_tryget` can return `ERR_PTR(-EIO)` (or similar). Since `ERR_PTR` values are non-NULL and non-zero, this `if` evaluates to true and `vga_tryget` returns `-EBUSY` instead of the actual error code. This is a bug -- `vga_tryget` should be updated to distinguish between a real conflict (non-NULL, non-ERR pointer) and an error (ERR_PTR). Something like:

```c
conflict = __vga_tryget(vgadev, rsrc);
if (IS_ERR(conflict))
    rc = PTR_ERR(conflict);
else if (conflict)
    rc = -EBUSY;
```

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