rtlwifi: halbtc8821a1ant: Remove set but unused variable 'wifi_rssi_state'

Fixes the following W=1 kernel build warning(s):

 drivers/net/wireless/realtek/rtlwifi/btcoexist/halbtc8821a1ant.c: In function ‘btc8821a1ant_run_coexist_mechanism’:
 drivers/net/wireless/realtek/rtlwifi/btcoexist/halbtc8821a1ant.c:1904:5: warning: variable ‘wifi_rssi_state’ set but not used [-Wunused-but-set-variable]

Cc: Ping-Ke Shih <pkshih@realtek.com>
Cc: Kalle Valo <kvalo@codeaurora.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Larry Finger <Larry.Finger@lwfinger.net>
Cc: linux-wireless@vger.kernel.org
Cc: netdev@vger.kernel.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20201102112410.1049272-28-lee.jones@linaro.org

drivers/net/wireless/realtek/rtlwifi/btcoexist/halbtc8821a1ant.c

@@ -1901,7 +1901,6 @@ static void btc8821a1ant_run_coexist_mechanism(struct btc_coexist *btcoexist)
 	bool increase_scan_dev_num = false;
 	bool bt_ctrl_agg_buf_size = false;
 	u8 agg_buf_size = 5;
-	u8 wifi_rssi_state = BTC_RSSI_STATE_HIGH;
 	u32 wifi_link_status = 0;
 	u32 num_of_wifi_link = 0;
 	bool wifi_under_5g = false;
@@ -1962,8 +1961,7 @@ static void btc8821a1ant_run_coexist_mechanism(struct btc_coexist *btcoexist)
 		btc8821a1ant_limited_tx(btcoexist, NORMAL_EXEC, 0, 0, 0, 0);
 	} else {
 		if (wifi_connected) {
-			wifi_rssi_state =
-				btc8821a1ant_wifi_rssi_state(btcoexist, 1, 2,
+			btc8821a1ant_wifi_rssi_state(btcoexist, 1, 2,
 							     30, 0);
 			btc8821a1ant_limited_tx(btcoexist,
 						NORMAL_EXEC, 1, 1,