mac80211: add APIs to allow keeping connections after WoWLAN

In order to be able to (securely) keep connections alive after
the system was suspended for WoWLAN, we need some additional
APIs. We already have API (ieee80211_gtk_rekey_notify) to tell
wpa_supplicant about the new replay counter if GTK rekeying
was done by the device while the host was asleep, but that's
not sufficient.

If GTK rekeying wasn't done, we need to tell the host about
sequence counters for the GTK (and PTK regardless of rekeying)
that was used while asleep, add ieee80211_set_key_rx_seq() for
that.

If GTK rekeying was done, then we need to be able to disable
the old keys (with ieee80211_remove_key()) and allocate the
new GTK key(s) in mac80211 (with ieee80211_gtk_rekey_add()).

If protocol offload (e.g. ARP) is implemented, then also the
TX sequence counter for the PTK must be updated, using the new
ieee80211_set_key_tx_seq() function.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>