mac80211: factor out plink event gathering

Signed-off-by: Thomas Pedersen <thomas@cozybit.com>
mac80211: initialize llid

If the peer doesn't have an llid for us, the event
gathering function won't use it anyway (based on
frametype), but initialize it so gcc and coverity don't
complain.

Signed-off-by: Thomas Pedersen <thomas@cozybit.com>