wifi: rtw88: coex: Prevent doing I/O during Wi-Fi power saving

wifi: rtw88: coex: Prevent doing I/O during Wi-Fi power saving

Fix Wi-Fi 2.4Ghz throughput drop over than 40% when Bluetooh is idle.
The code flow will read registers during Wi-Fi power saving, and be
returned, which results in incorrect counters to do mechanism judgment.
Adjust the code flow. Will leave Wi-Fi power save mode first then update
counters.

Signed-off-by: Ching-Te Ku <ku920601@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://msgid.link/20240320075047.31810-1-pkshih@realtek.com