net: libwx: fix alloc msix vectors failed

driver needs queue msix vectors and one misc irq vector,
but only queue vectors need irq affinity.
when num_online_cpus is less than chip max msix vectors,
driver will acquire (num_online_cpus + 1) vecotrs, and
call pci_alloc_irq_vectors_affinity functions with affinity
params without setting pre_vectors or post_vectors, it will
cause return error code -ENOSPC.
Misc irq vector is vector 0, driver need to set affinity params
.pre_vectors = 1.

Fixes: 3f703186 ("net: libwx: Add irq flow functions")
Signed-off-by: Duanqiang Wen <duanqiangwen@net-swift.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/wangxun/libwx/wx_lib.c

@@ -1598,7 +1598,7 @@ static void wx_set_num_queues(struct wx *wx)
  */
 static int wx_acquire_msix_vectors(struct wx *wx)
 {
-	struct irq_affinity affd = {0, };
+	struct irq_affinity affd = { .pre_vectors = 1 };
 	int nvecs, i;
 
 	/* We start by asking for one vector per queue pair */