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

 drivers/net/wireless/realtek/rtlwifi/btcoexist/halbtc8821a2ant.c: In function ‘btc8821a2ant_action_bt_inquiry’:
 drivers/net/wireless/realtek/rtlwifi/btcoexist/halbtc8821a2ant.c:1451:40: warning: variable ‘bt_rssi_state’ set but not used [-Wunused-but-set-variable]
 drivers/net/wireless/realtek/rtlwifi/btcoexist/halbtc8821a2ant.c:1451:22: warning: variable ‘wifi_rssi_state1’ set but not used [-Wunused-but-set-variable]
 drivers/net/wireless/realtek/rtlwifi/btcoexist/halbtc8821a2ant.c:1451:5: warning: variable ‘wifi_rssi_state’ set but not used [-Wunused-but-set-variable]
 drivers/net/wireless/realtek/rtlwifi/btcoexist/halbtc8821a2ant.c: In function ‘btc8821a2ant_action_wifi_idle_process’:
 drivers/net/wireless/realtek/rtlwifi/btcoexist/halbtc8821a2ant.c:1519:40: warning: variable ‘bt_rssi_state’ set but not used [-Wunused-but-set-variable]
 drivers/net/wireless/realtek/rtlwifi/btcoexist/halbtc8821a2ant.c:1519:5: warning: variable ‘wifi_rssi_state’ set but not used [-Wunused-but-set-variable]
 drivers/net/wireless/realtek/rtlwifi/btcoexist/halbtc8821a2ant.c: In function ‘btc8821a2ant_action_pan_hs’:
 drivers/net/wireless/realtek/rtlwifi/btcoexist/halbtc8821a2ant.c:2990:22: warning: variable ‘wifi_rssi_state1’ set but not used [-Wunused-but-set-variable]
 drivers/net/wireless/realtek/rtlwifi/btcoexist/halbtc8821a2ant.c: In function ‘btc8821a2ant_action_hid_a2dp’:
 drivers/net/wireless/realtek/rtlwifi/btcoexist/halbtc8821a2ant.c:3277:22: warning: variable ‘wifi_rssi_state1’ 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/20201102112410.1049272-31-lee.jones@linaro.org