wifi: cfg80211: use kfree_sensitive() for connkeys cleanup

wifi: cfg80211: use kfree_sensitive() for connkeys cleanup

The nl80211_parse_connkeys() function currently uses kfree() to release
the 'result' structure in error handling paths. However, if an error
occurs due to result->def being less than 0, the 'result' structure may
contain sensitive information.

To prevent potential leakage of sensitive data, replace kfree() with
kfree_sensitive() when freeing 'result'. This change aligns with the
approach used in its caller, nl80211_join_ibss(), enhancing the overall
security of the wireless subsystem.

Signed-off-by: Zilin Guan <zilin@seu.edu.cn>
Link: https://patch.msgid.link/20250523110156.4017111-1-zilin@seu.edu.cn
Signed-off-by: Johannes Berg <johannes.berg@intel.com>