xfrm: fix ptr_ret.cocci warnings

net/xfrm/xfrm_interface.c:692:1-3: WARNING: PTR_ERR_OR_ZERO can be used

 Use PTR_ERR_OR_ZERO rather than if(IS_ERR(...)) + PTR_ERR

Generated by: scripts/coccinelle/api/ptr_ret.cocci

Fixes: 44e2b838 ("xfrm: Return detailed errors from xfrmi_newlink")
CC: Benedict Wong <benedictwong@google.com>
Signed-off-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

net/xfrm/xfrm_interface.c

@@ -689,10 +689,7 @@ static int xfrmi_newlink(struct net *src_net, struct net_device *dev,
 	nla_strlcpy(p->name, tb[IFLA_IFNAME], IFNAMSIZ);
 
 	xi = xfrmi_locate(net, p, 1);
-	if (IS_ERR(xi))
-		return PTR_ERR(xi);
-
-	return 0;
+	return PTR_ERR_OR_ZERO(xi);
 }
 
 static void xfrmi_dellink(struct net_device *dev, struct list_head *head)