Claude review: drm/panfrost: Check another bo field for cache option query

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

Patch Review

**Verdict: Correct fix, but commit message could be clearer.**

The existing code:
```c
if (!bo->base.map_wc)
    args->create_flags |= PANFROST_BO_WB_MMAP;
```

This is indeed wrong. Looking at the source tree, `map_wc` is set by `should_map_wc()` which returns `false` for both coherent devices (where WC is impossible) AND for `wb_mmap` BOs. So on a coherent device, `!map_wc` is always true, meaning every BO would erroneously report `PANFROST_BO_WB_MMAP`. The fix to use `bo->wb_mmap` directly is correct — it reflects the actual creation flag:

```c
if (bo->wb_mmap)
    args->create_flags |= PANFROST_BO_WB_MMAP;
```

**Nit:** The commit message says "is recorded in a Panfrost BO's wb_mmap field" but doesn't explain *why* `!map_wc` was wrong. On a coherent device, `map_wc` is always false (line 460 in `panfrost_gem.c`), so `!map_wc` is always true — the old code would report all BOs as `WB_MMAP` on coherent devices. Explaining this would help reviewers.

---

---
Generated by Claude Code Patch Reviewer