rtw89: get channel parameters of 160MHz bandwidth

Calculate the offset of center and primary frequencies to get hardware
indices of center channel and primary channel, and then use them to
configure hardware to a specific channel.

Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220222032103.29392-1-pkshih@realtek.com