drm: Fix memory leak in drm_mode_setcrtc()

The mode passed to the .set_config() hook was never freed. The drivers
will make a copy of the mode, so simply free it when done.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/drm_crtc.c

@@ -643,6 +643,9 @@ EXPORT_SYMBOL(drm_mode_create);
  */
 void drm_mode_destroy(struct drm_device *dev, struct drm_display_mode *mode)
 {
+	if (!mode)
+		return;
+
 	drm_mode_object_put(dev, &mode->base);
 
 	kfree(mode);
@@ -1812,6 +1815,11 @@ int drm_mode_setcrtc(struct drm_device *dev, void *data,
 		}
 
 		mode = drm_mode_create(dev);
+		if (!mode) {
+			ret = -ENOMEM;
+			goto out;
+		}
+
 		drm_crtc_convert_umode(mode, &crtc_req->mode);
 		drm_mode_set_crtcinfo(mode, CRTC_INTERLACE_HALVE_V);
 	}
@@ -1881,6 +1889,7 @@ int drm_mode_setcrtc(struct drm_device *dev, void *data,
 
 out:
 	kfree(connector_set);
+	drm_mode_destroy(dev, mode);
 	mutex_unlock(&dev->mode_config.mutex);
 	return ret;
 }