drm/i915: Convert flip_work to a list.

This will be required to allow more than 1 update in the future.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1463490484-19540-10-git-send-email-maarten.lankhorst@linux.intel.com
Reviewed-by: Patrik Jakobsson <patrik.jakobsson@linux.intel.com>
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 9502e79..cec2deb 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -641,7 +641,7 @@
 	unsigned long enabled_power_domains;
 	bool lowfreq_avail;
 	struct intel_overlay *overlay;
-	struct intel_flip_work *flip_work;
+	struct list_head flip_work;
 
 	atomic_t unpin_work_count;
 
@@ -970,6 +970,8 @@
 }
 
 struct intel_flip_work {
+	struct list_head head;
+
 	struct work_struct unpin_work;
 	struct work_struct mmio_work;