ath11k: change management tx queue to avoid connection timed out

In the phase of wlan load, it has hw scan and 11d scan which sent to
firmware by ath11k, then hw scan and 11d scan will use about 14 seconds,
and meanwhile ath11k_reg_update_chan_list() is running in workqueue of
ath11k_base, and wait for 11d scan/hw scan finished. When the hw scan
finished, mac80211 will start to connect and send management packet,
at this moment, ath11k_reg_update_chan_list() is still waiting for 11d
scan finished, so wmi_mgmt_tx_work of ath11k will not run and thus the
tx management packet also not send out and lead authentication timed
out.

log:
INFO kernel: [  187.885322] wlan0: authenticate with 72:6c:57:43:9f:90
INFO kernel: [  187.937266] wlan0: send auth to 72:6c:57:43:9f:90 (try 1/3)
INFO kernel: [  188.626944] wlan0: send auth to 72:6c:57:43:9f:90 (try 2/3)
INFO kernel: [  189.650999] wlan0: send auth to 72:6c:57:43:9f:90 (try 3/3)
INFO kernel: [  190.651917] wlan0: authentication with 72:6c:57:43:9f:90 timed out

Change wmi_mgmt_tx_work to another queue workqueue_aux of ath11k_base,
then connection success.

Tested-on: WCN6855 hw2.0 PCI WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3
Signed-off-by: Wen Gong <quic_wgong@quicinc.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20220428023320.4007-1-quic_wgong@quicinc.com

drivers/net/wireless/ath/ath11k/mac.c

@@ -5592,7 +5592,7 @@ static int ath11k_mac_mgmt_tx(struct ath11k *ar, struct sk_buff *skb,
 
 	skb_queue_tail(q, skb);
 	atomic_inc(&ar->num_pending_mgmt_tx);
-	queue_work(ar->ab->workqueue, &ar->wmi_mgmt_tx_work);
+	queue_work(ar->ab->workqueue_aux, &ar->wmi_mgmt_tx_work);
 
 	return 0;
 }