iser-target: Fix smatch warning

Unused return value from down_interruptible
Reported-by: NOr Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: NSagi Grimberg <sagig@mellanox.com>
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

drivers/infiniband/ulp/isert/ib_isert.c

@@ -3152,7 +3152,7 @@ isert_accept_np(struct iscsi_np *np, struct iscsi_conn *conn)
 
 accept_wait:
 	ret = down_interruptible(&isert_np->np_sem);
-	if (max_accept > 5)
+	if (ret || max_accept > 5)
 		return -ENODEV;
 
 	spin_lock_bh(&np->np_thread_lock);