Claude review: drm/damage-helper: Do not alter damage clips on modeset, but ignore them

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

Patch Review

**Correctly tagged for stable (v6.10+).** Fixes the Fixes: tag target.

The change from destroying the blob to setting `ignore_damage_clips = true` is correct and preserves damage information for drivers that can use it even during modesets:

```c
-		if (drm_atomic_crtc_needs_modeset(crtc_state)) {
-			drm_property_blob_put(plane_state->fb_damage_clips);
-			plane_state->fb_damage_clips = NULL;
-		}
+		if (drm_atomic_crtc_needs_modeset(crtc_state))
+			plane_state->ignore_damage_clips = true;
```

The addition of `state->ignore_damage_clips = false` in `__drm_atomic_helper_plane_duplicate_state` is the **actual bug fix** -- without it, `ignore_damage_clips` would carry over from the duplicated state, potentially causing all subsequent updates to skip damage clips. Good catch.

The new kunit test `drm_test_damage_iter_damage_ignore` correctly validates the flag by setting two damage clips plus the flag and verifying full-framebuffer damage is returned.

**No issues.**

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Generated by Claude Code Patch Reviewer