drm/i915: Drop irqsave/restore for flip_done_handler()

Since flip_done_handler() is always called from the irq handler
we can skip the irqsave/restore dance.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230928152450.30109-2-ville.syrjala@linux.intel.comReviewed-by: Arun R Murthy <arun.r.murthy@intel.com>

drivers/gpu/drm/i915/display/intel_display_irq.c

@@ -340,17 +340,15 @@ static void flip_done_handler(struct drm_i915_private *i915,
 			      enum pipe pipe)
 {
 	struct intel_crtc *crtc = intel_crtc_for_pipe(i915, pipe);
-	struct drm_device *dev = &i915->drm;
-	unsigned long irqflags;
 
-	spin_lock_irqsave(&dev->event_lock, irqflags);
+	spin_lock(&i915->drm.event_lock);
 
 	if (crtc->flip_done_event) {
 		drm_crtc_send_vblank_event(&crtc->base, crtc->flip_done_event);
 		crtc->flip_done_event = NULL;
 	}
 
-	spin_unlock_irqrestore(&dev->event_lock, irqflags);
+	spin_unlock(&i915->drm.event_lock);
 }
 
 static void hsw_pipe_crc_irq_handler(struct drm_i915_private *dev_priv,