Claude review: drm/atomic: Call complete_signaling only if prepare_signaling is done

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

Patch Review

```c
-	complete_signaling(dev, state, fence_state, num_fences, !ret);
+	if (num_fences)
+		complete_signaling(dev, state, fence_state, num_fences, !ret);
```

This is needed because patch 4 moves the state allocation earlier, so error paths now reach `out:` before `prepare_signaling` runs. The check is reasonable since `num_fences` is now initialized to 0.

However, `complete_signaling` also handles cleanup of `crtc_state->event` when `install_fds` is false (error path). Skipping it entirely when `num_fences == 0` could miss that event cleanup if we've partially set up state but never called `prepare_signaling`. Looking at the code, events are only set up inside `prepare_signaling`, so this should be safe. But a comment explaining why this is safe would help.

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Generated by Claude Code Patch Reviewer