rtlwifi: btcoex: 21a 2ant: monitor if bt is slave or not

We monitor the packet counter to guess if the bt is slave or not, and
when bt is slave, it may receive packet at any time, so we will have to
take care about it

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>