rtw89: coex: Update COEX to 5.5.8

Update COEX version.

Signed-off-by: Ching-Te Ku <ku920601@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/20211209083229.10815-8-pkshih@realtek.com