wifi: rtw89: phy: change naming related BT coexistence functions

wifi: rtw89: phy: change naming related BT coexistence functions

Change naming to disambiguate the functions because their names are common
and not clear about the purpose. Not change logic at all.

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://lore.kernel.org/r/20231016065115.751662-2-pkshih@realtek.com