mac80211: Move up init of TXQs

On init, ieee80211_if_add() dumps the interface. Since that now includes a
dump of the TXQ state, we need to initialise that before the dump happens.
So move up the TXQ initialisation to to before the call to
ieee80211_if_add().

Fixes: 52539ca8

 ("cfg80211: Expose TXQ stats and parameters to userspace")
Reported-by: Niklas Cassel <niklas.cassel@linaro.org>
Signed-off-by: Toke Høiland-Jørgensen <toke@toke.dk>
Tested-by: Niklas Cassel <niklas.cassel@linaro.org>
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>