Claude review: drm/mode-config: Create drm_mode_config_create_state()

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

Patch Review

**This is the key patch of the series.** Creates `drm_mode_config_create_state()` which iterates all DRM objects and creates initial state via the `atomic_create_state` callbacks, skipping objects that already have state.

**Critical issue - missing error cleanup**: When `drm_mode_config_create_state()` fails partway through (e.g., an allocation failure for a connector after planes and CRTCs already got their states allocated), the already-allocated states are not cleaned up:
```c
drm_for_each_connector_iter(connector, &conn_iter) {
    ...
    ret = drm_mode_config_connector_create_state(connector);
    if (ret)
        return ret;  // leaks previously allocated states
}
drm_connector_list_iter_end(&conn_iter);
```
Additionally, returning early from the `drm_for_each_connector_iter` loop without calling `drm_connector_list_iter_end()` will leak the iterator's reference. This needs to be fixed -- either `goto` to cleanup code that calls `drm_connector_list_iter_end()`, or restructure the error path.

The doc update to `drm_atomic.c` (lifetime description) is a nice clarification.

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Generated by Claude Code Patch Reviewer