drm/i915: Add display hotplug event on Ironlake

Enable display hotplug irqs from Ibex Peak (PCH).

Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 210d0f6..835625b 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -214,6 +214,8 @@
 	u32 gt_irq_mask_reg;
 	u32 gt_irq_enable_reg;
 	u32 de_irq_enable_reg;
+	u32 pch_irq_mask_reg;
+	u32 pch_irq_enable_reg;
 
 	u32 hotplug_supported_mask;
 	struct work_struct hotplug_work;