wifi: rtw89: 8922a: add BTG functions to assist BT coexistence to control TX/RX

These functions are to control baseband AGC while BT coexists with WiFi.
Among these functions, ctrl_btg_bt_rx is used to control AGC related
settings, which is affected by BT RX, while BT shares the same path with
WiFi; ctrl_nbtg_bt_tx is used to control AGC settings under non-shared
path condition, which is affected by BT TX.

Signed-off-by: Chung-Hsuan Hung <hsuan8331@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://msgid.link/20240120003831.7014-7-pkshih@realtek.com