rtw88: coex: 8821c: correct antenna switch function

This patch fixes a defect that uses incorrect function to access
registers. Use 8 and 32 bit access function to access 8 and 32 bit long
data respectively.

Signed-off-by: Guo-Feng Fan <vincent_fann@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210202055012.8296-2-pkshih@realtek.com