wifi: rtw89: support TX diversity for 1T2R chipset

Check RSSI strength to decide which path is better, and then set TX path
accordingly.

Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220908074140.39776-6-pkshih@realtek.com