mac80211: remove mysterious peering ie_len check

According to IEEE802.11-2012 (8.4.2.104), no peering
management element exists with length 7. This code seems
to have been part of the original implementation, but it's
purpose is now unknown, so remove it.

Signed-off-by: Thomas Pedersen <thomas@cozybit.com>
mac80211: factor out plink event gathering
mac80211: consolidate process_plink_frame unlocks
mac80211: initialize sta plid early
mac80211: initialize llid
mac80211: factor out peering FSM from process_frame
mac80211: consolidate calls to plink_frame_tx
mac80211: avoid transmitting peering close frames twice
mac80211: peering fsm formatting
mac80211: remove false annotation