rtw89: 8852c: adjust mactxen delay of mac/phy interface

mac_txen time is to inform TMAC tx after rx air end.
Modify 8852c value to meet TB SIFS time.

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/20220704023453.19935-7-pkshih@realtek.com