IB/usnic: delete unneeded IS_ERR test

kzalloc doesn't return ERR_PTR, so there is no need to test for it.

The semantic match that finds this problem is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@@
expression x,e;
@@

* x = kzalloc(...)
... when != x = e
* IS_ERR_OR_NULL(x)
// </smpl>
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Reviewed-by: Dave Goodell <dgoodell@cisco.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/usnic/usnic_ib_verbs.c

@@ -625,8 +625,8 @@ struct ib_mr *usnic_ib_reg_mr(struct ib_pd *pd, u64 start, u64 length,
 			virt_addr, length);
 
 	mr = kzalloc(sizeof(*mr), GFP_KERNEL);
-	if (IS_ERR_OR_NULL(mr))
-		return ERR_PTR(mr ? PTR_ERR(mr) : -ENOMEM);
+	if (!mr)
+		return ERR_PTR(-ENOMEM);
 
 	mr->umem = usnic_uiom_reg_get(to_upd(pd)->umem_pd, start, length,
 					access_flags, 0);