drm/i915: add per-output hotplug callback for KMS

This allows each output to deal with plug/unplug events as needed.

Signed-off-by: Keith Packard <keithp@keithp.com>
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index d89a2fe..c585879 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -83,6 +83,7 @@
 	bool load_detect_temp;
 	bool needs_tv_clock;
 	void *dev_priv;
+	void (*hot_plug)(struct intel_output *);
 };
 
 struct intel_crtc {