wifi: rtw89: add MLO track for MLSR switch decision

Add MLSR switch mechanism based on tracking RSSI. Switch to a 2 GHz link
(if any) when average RSSI is lower than threshold -53. And, switch out
from a 2 GHz link when average RSSI is larger than threshold -38.

The sequence of MLSR switch handling is like the following.
1. initialize target link and configure to PS mode
2. configure current designated link to PS mode
3. configure target link to non-PS mode
4. deinitialize currently active links except target link

The above flow also implies that target link becomes new designated link.

Signed-off-by: Po-Hao Huang <phhuang@realtek.com>
Signed-off-by: Zong-Zhe Yang <kevin_yang@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/20250505072440.45113-7-pkshih@realtek.com