wifi: rtw88: add mutex when set SAR

Applying SAR will access hal data, it should hold rtwdev::mutex
to avoid hal data changed during setting flow.
Signed-off-by: Chih-Kang Chang <gary.chang@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220809084107.38137-2-pkshih@realtek.com

drivers/net/wireless/realtek/rtw88/mac80211.c

@@ -875,7 +875,9 @@ static int rtw_ops_set_sar_specs(struct ieee80211_hw *hw,
 {
 	struct rtw_dev *rtwdev = hw->priv;
 
+	mutex_lock(&rtwdev->mutex);
 	rtw_set_sar_specs(rtwdev, sar);
+	mutex_unlock(&rtwdev->mutex);
 
 	return 0;
 }