ath11k: change to treat alpha code na as world wide regdomain

Some firmware versions for WCN6855 report the default regdomain with
alpha code "na" by default when load as a world wide regdomain, ath11k
should treat it as a world wide alpha code.

Tested-on: WCN6855 hw2.0 PCI WLAN.HSP.1.1-01720.1-QCAHSPSWPL_V1_V2_SILICONZ_LITE-1
Signed-off-by: Wen Gong <quic_wgong@quicinc.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20211118094848.7776-1-quic_wgong@quicinc.com

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

@@ -5927,7 +5927,13 @@ static void ath11k_wmi_htc_tx_complete(struct ath11k_base *ab,
 
 static bool ath11k_reg_is_world_alpha(char *alpha)
 {
-	return alpha[0] == '0' && alpha[1] == '0';
+	if (alpha[0] == '0' && alpha[1] == '0')
+		return true;
+
+	if (alpha[0] == 'n' && alpha[1] == 'a')
+		return true;
+
+	return false;
 }
 
 static int ath11k_reg_chan_list_event(struct ath11k_base *ab, struct sk_buff *skb)