mac80211: provide race-free 64-bit traffic counters

Make the TX bytes/packets counters race-free by keeping
them per AC so concurrent TX on queues can't cause lost
or wrong updates. This works since each station belongs
to a single interface. While at it also make the bytes
counters 64-bit.

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

diff --cc net/mac80211/cfg.c
Simple merge

diff --cc net/mac80211/sta_info.h
Simple merge

diff --cc net/mac80211/tx.c
Simple merge