[][MAC80211][WiFi6][mt76][Add post channel switch callback for DFS channel switch support]

[Description]
Add post channel switch callback for DFS channel switch support
After CAC, we need to set channel again for dfs RDD (notify to change
state from cac to active)

[Release-log]
N/A

Change-Id: I6566a6a0a7463cd89744e30f3b5a1c8a31d4dabe
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/8260502
1 file changed