wifi: rtw89: phy: set TX power by rate according to chip gen

Wi-Fi 6 chips and Wi-Fi 7 chips have different register design for
TX power by rate. We rename original setting stuffs with a suffix
`_ax` and implement setting flow for Wi-Fi 7 chips. Then, we set TX
power by rate according to chip generation.

Signed-off-by: Zong-Zhe Yang <kevin_yang@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/20231003015446.14658-3-pkshih@realtek.com