rtlwifi: btcoex: Add interaction with phydm

Get phydm's counter and version from the module phydm that is not
submitted so we implement dummy functions.

Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Acked-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>