rtw89: add chip_info::{h2c,c2h}_reg to support more chips

This is a register-based H2C/C2H interface to exchange data with firmware.
Since the register addresses of 8852A and 8852C are different, add fields
to chip_info to support this.

Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220307060457.56789-9-pkshih@realtek.com