rtw88: coex: change the parameter for A2DP when WLAN connecting

The original mechanism may cause A2DP glitch during WiFi connecting AP.
Because the original TDMA may decrease too much A2DP slot.
This patch add a timer and variable to let the case A2DP + WL_Connecting
performed more well.

Signed-off-by: Ching-Te Ku <ku920601@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20201109085909.9143-9-pkshih@realtek.com