wifi: cfg80211: clear link ID from bitmap during link delete after clean up

In the Linux kernel, the following vulnerability has been resolved:

wifi: cfg80211: clear link ID from bitmap during link delete after clean up

Currently, during link deletion, the link ID is first removed from the

valid_links bitmap before performing any clean-up operations. However, some

functions require the link ID to remain in the valid_links bitmap. One

such example is cfg80211_cac_event(). The flow is -

nl80211_remove_link()

cfg80211_remove_link()

ieee80211_del_intf_link()

ieee80211_vif_set_links()

ieee80211_vif_update_links()

ieee80211_link_stop()

cfg80211_cac_event()

cfg80211_cac_event() requires link ID to be present but it is cleared

already in cfg80211_remove_link(). Ultimately, WARN_ON() is hit.

Therefore, clear the link ID from the bitmap only after completing the link

clean-up.