drm/i915: simplify i915_reset a bit

- need_display is always true, scrap it.
- don't reacquire the mutex to do nothing after having restored the
  gem state.
Reviewed-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.c

@@ -787,11 +787,6 @@ static int gen6_do_reset(struct drm_device *dev, u8 flags)
 int i915_reset(struct drm_device *dev, u8 flags)
 {
 	drm_i915_private_t *dev_priv = dev->dev_private;
-	/*
-	 * We really should only reset the display subsystem if we actually
-	 * need to
-	 */
-	bool need_display = true;
 	int ret;
 
 	if (!i915_try_reset)
@@ -865,22 +860,18 @@ int i915_reset(struct drm_device *dev, u8 flags)
 		drm_irq_uninstall(dev);
 		drm_mode_config_reset(dev);
 		drm_irq_install(dev);
-
-		mutex_lock(&dev->struct_mutex);
-	}
-
+	} else {
 		mutex_unlock(&dev->struct_mutex);
+	}
 
 	/*
 	 * Perform a full modeset as on later generations, e.g. Ironlake, we may
 	 * need to retrain the display link and cannot just restore the register
 	 * values.
 	 */
-	if (need_display) {
 	mutex_lock(&dev->mode_config.mutex);
 	drm_helper_resume_force_mode(dev);
 	mutex_unlock(&dev->mode_config.mutex);
-	}
 
 	return 0;
 }