drm/i915: Initialize overlay->last_flip properly

Initialize overlay->last_flip properly instead of leaving it zeroed.

Cc: stable@vger.kernel.org
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Fixes: 0d9bdd88 ("drm/i915: Convert intel_overlay to request tracking")
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161221144547.27319-1-ville.syrjala@linux.intel.com
(cherry picked from commit 330afdb1)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/intel_overlay.c

@@ -1430,6 +1430,8 @@ void intel_setup_overlay(struct drm_i915_private *dev_priv)
 	overlay->contrast = 75;
 	overlay->saturation = 146;
 
+	init_request_active(&overlay->last_flip, NULL);
+
 	regs = intel_overlay_map_regs(overlay);
 	if (!regs)
 		goto out_unpin_bo;