wifi: rtw89: 8922a: add power on/off functions

The power on/off functions are to turn on hardware function blocks and
to turn off them if we are going to stay in idle state.

Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://msgid.link/20231211083341.118047-3-pkshih@realtek.com