drm/i915: Don't leak VBT mode data

We allocate memory for LVDS modes while parsing the VBT at startup, but
never free this memory when the driver is unloaded, causing a small
leak.

Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/i915_dma.c

@@ -1137,6 +1137,10 @@ int i915_driver_unload(struct drm_device *dev)
 		dev_priv->vbt.child_dev = NULL;
 		dev_priv->vbt.child_dev_num = 0;
 	}
+	kfree(dev_priv->vbt.sdvo_lvds_vbt_mode);
+	dev_priv->vbt.sdvo_lvds_vbt_mode = NULL;
+	kfree(dev_priv->vbt.lfp_lvds_vbt_mode);
+	dev_priv->vbt.lfp_lvds_vbt_mode = NULL;
 
 	vga_switcheroo_unregister_client(dev->pdev);
 	vga_client_register(dev->pdev, NULL, NULL, NULL);