net: xenbus: remove redundant condition check before debugfs_remove_recursive

debugfs_remove_recursive has taken the IS_ERR_OR_NULL into account. Just
remove the unnecessary condition check.
Signed-off-by: zhong jiang <zhongjiang@huawei.com>
Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/xen-netback/xenbus.c

@@ -254,7 +254,6 @@ static void xenvif_debugfs_delif(struct xenvif *vif)
 	if (IS_ERR_OR_NULL(xen_netback_dbg_root))
 		return;
 
-	if (!IS_ERR_OR_NULL(vif->xenvif_dbg_root))
 	debugfs_remove_recursive(vif->xenvif_dbg_root);
 	vif->xenvif_dbg_root = NULL;
 }