drm/vmwgfx: unlock on error path in vmw_execbuf_process()

There is a missing unlock on error here.

Fixes: 30f82d8 ('drm/vmwgfx: Reemit context bindings when necessary v2')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>

drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c

@@ -2469,7 +2469,7 @@ int vmw_execbuf_process(struct drm_file *file_priv,
 	if (dev_priv->has_mob) {
 		ret = vmw_rebind_contexts(sw_context);
 		if (unlikely(ret != 0))
-			goto out_err;
+			goto out_unlock_binding;
 	}
 
 	cmd = vmw_fifo_reserve(dev_priv, command_size);