rtw89: 8852c: add 8852c specific BT-coexistence initial function

Initialize registers to default values, such as PTA and GNT pin, and set
pin MUX according to number of antenna on hardware module.

Signed-off-by: Chia-Yuan Li <leo.li@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/20220408001353.17188-10-pkshih@realtek.com