LinuxKPI: 80211 / iwlwifi: improve queue management

For one initialise vif->hw_queues later set in lkpi_80211_txq_tx_one()
for drivers using them. This may still need slightly more cleanup once
we get QUEUE_CONTROL-supporting drivers into the tree.

For the other rework and improve how we deal with tid/ac/txq in
lkpi_80211_txq_tx_one() and cleanup old comments and unused code.
This seems to reduce (remove) "Invalid TXQ id" reports from iwlwifi.
(The assumption is that the frame(s) triggering this WARN_ONCE or the
added FreeBSD specific logging were sent with lkpi_80211_mo_tx()).

Adjust the one logging from e674ddec0b4138274539587fe9336b577ff1242a
to IWL_DEBUG_TX so that now this is fixed it is also not always logged
anymore but leave it in case we need to further debug queues in the
future.

Tested by: pstef, Kevin Oberman (rkoberman gmail.com)
Sponsored by: The FreeBSD Foundation

(cherry picked from commit e3a0b1202bf63f4b412e02eb6edc0fb1f64313de)