rtlwifi: btcoex: add boolean variables dbg_mode

In files halbtc8822b1ant.c and halbtc8822b2ant.c that I will submit later,
two undesired directives named BT_8822B_1ANT_COEX_DBG and
BT_8822B_2ANT_COEX_DBG will be replaced by boolean variables.

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>