wifi: rtw89: coex: Fix test fail when coexist with raspberryPI A2DP idle

The origin code will enable TDMA WL:BT = 50:50 to prevent Wi-Fi
throughput suddenly drop to 0 in the moment while A2DP pause.
And this protection just a short moment, and will turn to Bluetooth
idle case when A2DP turn into sniff mode. But the raspberryPI simulated
A2DP device will not turn into sniff mode. So the protection will bring
the throughput drop.

Signed-off-by: Ching-Te Ku <ku920601@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230117114109.4298-8-pkshih@realtek.com