mac80211_hwsim: use GFP_ATOMIC under spin lock

A spin lock is taken here so we should use GFP_ATOMIC.

Fixes: 5d44fe7c ("mac80211_hwsim: add frame transmission support over virtio")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Link: https://lore.kernel.org/r/20200422020154.112088-1-weiyongjun1@huawei.comSigned-off-by: Johannes Berg <johannes.berg@intel.com>

drivers/net/wireless/mac80211_hwsim.c

@@ -4068,7 +4068,7 @@ static void hwsim_virtio_rx_work(struct work_struct *work)
 	}
 	vq = hwsim_vqs[HWSIM_VQ_RX];
 	sg_init_one(sg, skb->head, skb_end_offset(skb));
-	err = virtqueue_add_inbuf(vq, sg, 1, skb, GFP_KERNEL);
+	err = virtqueue_add_inbuf(vq, sg, 1, skb, GFP_ATOMIC);
 	if (WARN(err, "virtqueue_add_inbuf returned %d\n", err))
 		nlmsg_free(skb);
 	else