Claude review: drm/imagination: Update check to skip prepare_job() for fragment jobs

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

Patch Review

**Status**: Correct, minor optimization.

Changes from `job->paired_job->has_pm_ref` to `job->has_pm_ref`. Looking at `pvr_queue_run_job()` (line 776-779), both the geometry job and its paired fragment job get PM refs during `run_job()`:

```c
err = pvr_job_get_pm_ref(job);
...
if (job->paired_job) {
    err = pvr_job_get_pm_ref(job->paired_job);
```

So checking `job->has_pm_ref` (the fragment job itself) is equivalent and avoids a pointer dereference to the paired geometry job which might have already completed and released its PM ref by the time `prepare_job()` is called again on the fragment job.

**No issues.**

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Generated by Claude Code Patch Reviewer