hns_enet: use cpumask_var_t for on-stack mask

On large SMP builds, we can run into a build warning:

drivers/net/ethernet/hisilicon/hns/hns_enet.c: In function 'hns_set_irq_affinity.isra.27':
drivers/net/ethernet/hisilicon/hns/hns_enet.c:1242:1: warning: the frame size of 1032 bytes is larger than 1024 bytes [-Wframe-larger-than=]

The solution here is to use cpumask_var_t, which can use dynamic
allocation when CONFIG_CPUMASK_OFFSTACK is enabled.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/hisilicon/hns/hns_enet.c

@@ -1202,43 +1202,48 @@ static void hns_set_irq_affinity(struct hns_nic_priv *priv)
 	struct hns_nic_ring_data *rd;
 	int i;
 	int cpu;
-	cpumask_t mask;
+	cpumask_var_t mask;
+
+	if (!alloc_cpumask_var(&mask, GFP_KERNEL))
+		return;
 
 	/*diffrent irq banlance for 16core and 32core*/
 	if (h->q_num == num_possible_cpus()) {
 		for (i = 0; i < h->q_num * 2; i++) {
 			rd = &priv->ring_data[i];
 			if (cpu_online(rd->queue_index)) {
-				cpumask_clear(&mask);
+				cpumask_clear(mask);
 				cpu = rd->queue_index;
-				cpumask_set_cpu(cpu, &mask);
+				cpumask_set_cpu(cpu, mask);
 				(void)irq_set_affinity_hint(rd->ring->irq,
-							    &mask);
+							    mask);
 			}
 		}
 	} else {
 		for (i = 0; i < h->q_num; i++) {
 			rd = &priv->ring_data[i];
 			if (cpu_online(rd->queue_index * 2)) {
-				cpumask_clear(&mask);
+				cpumask_clear(mask);
 				cpu = rd->queue_index * 2;
-				cpumask_set_cpu(cpu, &mask);
+				cpumask_set_cpu(cpu, mask);
 				(void)irq_set_affinity_hint(rd->ring->irq,
-							    &mask);
+							    mask);
 			}
 		}
 
 		for (i = h->q_num; i < h->q_num * 2; i++) {
 			rd = &priv->ring_data[i];
 			if (cpu_online(rd->queue_index * 2 + 1)) {
-				cpumask_clear(&mask);
+				cpumask_clear(mask);
 				cpu = rd->queue_index * 2 + 1;
-				cpumask_set_cpu(cpu, &mask);
+				cpumask_set_cpu(cpu, mask);
 				(void)irq_set_affinity_hint(rd->ring->irq,
-							    &mask);
+							    mask);
 			}
 		}
 	}
+
+	free_cpumask_var(mask);
 }
 
 static int hns_nic_init_irq(struct hns_nic_priv *priv)