maintain key set/delete order

update setting key functions
style(9) related changes
garbage collection
remove redundant register configurations
redo setting AMPDU buffer size
reduce the calling frequency of run_drain_fifo()
update writing beacon

* correct txop for beacon
* stop beacon Tx while updating beacon, otherwise beacon may corrupt
* clear leftover bits, just in case (new beacon maybe shorter)
add missing parentheses
prevent from using GF phy when there is a non-HT node
increase Tx ring count to 64

enough to prevent "tx ring full"
to prevent LORs, call some functions without holding driver lock
increment Tx seq # when passing packets to USB stack