mac80211: use subqueue helpers

There are subqueue helpers so that we don't
need to get the TX queue and then wake/stop
it, use those helpers.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

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

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