Claude review: drm: bridge: dw_hdmi: Use delayed_work to debounce hotplug event

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

Patch Review

Introduces `delayed_work` for HPD debouncing with a 1100ms timeout. The work is disabled by default and only enabled via the `enable_hpd`/`hpd_enable` callbacks.

```c
+	INIT_DELAYED_WORK(&hdmi->hpd_work, dw_hdmi_hpd_work);
+	disable_delayed_work(&hdmi->hpd_work);
```

One observation about the `dw_hdmi_hpd_work` function:

```c
+	drm_helper_hpd_irq_event(hdmi->bridge.dev);
+	status = dw_hdmi_phy_read_hpd(hdmi, hdmi->phy.data);
+	drm_bridge_hpd_notify(&hdmi->bridge, status);
```

The `drm_helper_hpd_irq_event()` already calls the connector detect function, which in turn calls `dw_hdmi_connector_status_update()` to update EDID. Then `dw_hdmi_phy_read_hpd()` re-reads the HPD status. This means the status reported via `drm_bridge_hpd_notify()` could theoretically differ from what `drm_helper_hpd_irq_event()` observed, though in practice the 1100ms debounce should make this stable. This is a minor race but not a real problem. **No Reviewed-by yet.**

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