wifi: rtw89: 8852b: add functions to control BB to assist RF calibrations

When we are going to do RF calibrations, they need BB helpers to control
TX PLCP, power, path and mode. Also, it they need helpers to backup and
restore some registers before and after RF calibrations. Then, use flow of
RF calibrations will be like backup registers, configure calibration,
configure TX parameters, measure calibration result, and finally restore
registers.

Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20221009125403.19662-9-pkshih@realtek.com