rtlwifi: btcoex: 21a 2ant: ignore wifi if it is at 5G band

When wifi is at 5G band, it does not intefere with 2.4G bt signal,
hence we can just ignore it and transmit normally as nothing happened.

Signed-off-by: Yan-Hsuan Chuang <yhchuang@realtek.com>
Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Cc: Pkshih <pkshih@realtek.com>
Cc: Birming Chiu <birming@realtek.com>
Cc: Shaofu <shaofu@realtek.com>
Cc: Steven Ting <steventing@realtek.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>