wifi: rtw89: 8852b: add channel encoding for hw_scan

To obtain correct packet frequency for hw_scan, 52b needs to decode
the channel index obtained from hardware. Change the driver related
set channel part as well to make driver/firmware compatible.

Signed-off-by: Po-Hao Huang <phhuang@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/20230220070202.29868-5-pkshih@realtek.com