net: netcp: replace IS_ERR_OR_NULL by IS_ERR

knav_queue_open always returns an ERR_PTR value, never NULL.  This can be
confirmed by unfolding the function calls and conforms to the function's
documentation.  Thus, replace IS_ERR_OR_NULL by IS_ERR in error checks.

The change is made using the following semantic patch:
(http://coccinelle.lip6.fr/)

// <smpl>
@@
expression x;
statement S;
@@

x = knav_queue_open(...);
if (
-   IS_ERR_OR_NULL
+   IS_ERR
    (x)) S
// </smpl>

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>