Claude review: drm/panthor: Expose GPU page sizes to UM

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

Patch Review

This patch exposes the MMU page size bitmap to userspace via a new `DRM_PANTHOR_DEV_QUERY_MMU_INFO` query type and `struct drm_panthor_mmu_info`.

**uAPI enum value collision (major):** The new enum member is inserted between `DRM_PANTHOR_DEV_QUERY_CSIF_INFO` and `DRM_PANTHOR_DEV_QUERY_TIMESTAMP_INFO`. Since the enum is auto-numbered (only `GPU_INFO = 0` has an explicit value), this shifts the values of `TIMESTAMP_INFO` (2→3) and `GROUP_PRIORITIES_INFO` (3→4). Any existing userspace compiled with the old header will send the wrong query type for those two.

```c
+	/** @DRM_PANTHOR_DEV_QUERY_MMU_INFO: Query MMU information. */
+	DRM_PANTHOR_DEV_QUERY_MMU_INFO,
+
 	/** @DRM_PANTHOR_DEV_QUERY_TIMESTAMP_INFO: Query timestamp information. */
 	DRM_PANTHOR_DEV_QUERY_TIMESTAMP_INFO,
```

The new member should be appended **after** `DRM_PANTHOR_DEV_QUERY_GROUP_PRIORITIES_INFO` to preserve existing numeric values, or assigned an explicit value.

The rest of the patch is straightforward — `panthor_mmu_info_init()` sets the bitmap, the ioctl copies it out. Reviewed-by tags from Steven Price and Boris Brezillon are present.

---
Generated by Claude Code Patch Reviewer