In original code architecture, sec CAM is a component of addr CAM.
Hence, sec CAM could not be shared. After MLO, each link has its own
addr CAM. However, one MLD PTK takes only one sec CAM but it needs to
work on multiple links' addr CAMs. So, we now manage sec CAMs in global
pool, and each of them is not bound to a single addr CAM now.

before:

+-----------------+         +--------------------+
| rtw89_{vif/sta} |   ...   | ieee80211_key_conf |
+-----------------+         +--------------------+
        ^                              |
        V                              | hw_key_idx
        |                              |
        |                              V
        |                             +--
   +----------+   addr_cam::key_idx   |  \        +---------+
   | addr_cam |<>---------------------|   |-------| sec_cam |
   +----------+                       |  /        +---------+
                                      +--

after:

+----------------------+         +--------------------+
| rtw89_{vif/sta}_link |   ...   | ieee80211_key_conf |
+----------------------+         +--------------------+
        ^                                   |
        V                                   | hw_key_idx
        |                                   |
        |                                   V
        |                                  --+                  +---------+
        |              +---------+        /  |  sec_cam_idx     | global  |
        |              | sec_cam |-------|   |----------------<>| sec_cam |
        |              +---------+        \  |                  | pool    |
        |                   ^              --+                  +---------+
        |                   |
        |               (*) |
   +----------+             |
   | addr_cam |-------------+
   +----------+
Signed-off-by: Zong-Zhe Yang <kevin_yang@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://msgid.link/20240509090646.35304-3-pkshih@realtek.com