wifi: mac80211: Serialize ieee80211_handle_wake_tx_queue()

ieee80211_handle_wake_tx_queue must not run concurrent multiple times.
It calls ieee80211_txq_schedule_start() and the drivers migrated to iTXQ
do not expect overlapping drv_tx() calls.

This fixes 'c850e31f ("wifi: mac80211: add internal handler for
wake_tx_queue")', which introduced ieee80211_handle_wake_tx_queue.
Drivers started to use it with 'a790cc3a ("wifi: mac80211: add
wake_tx_queue callback to drivers")'.
But only after fixing an independent bug with
'4444bc21 ("wifi: mac80211: Proper mark iTXQs for resumption")'
problematic concurrent calls really happened and exposed the initial
issue.

Fixes: c850e31f

 ("wifi: mac80211: add internal handler for wake_tx_queue")
Reported-by: Thomas Mann <rauchwolke@gmx.net>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=217119
Link: https://lore.kernel.org/r/b8efebc6-4399-d0b8-b2a0-66843314616b@leemhuis.info/
Link: https://lore.kernel.org/r/b7445607128a6b9ed7c17fcdcf3679bfaf4aaea.camel@sipsolutions.net>
CC: <stable@vger.kernel.org>
Signed-off-by: Alexander Wetzel <alexander@wetzel-home.de>
Link: https://lore.kernel.org/r/20230314211122.111688-1-alexander@wetzel-home.de
[add missing spin_lock_init() noticed by Felix]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>