Move AP BSS configuration parameters into set_ap()

Move AP BSS configuration parameters into set_ap()

Remove the separate driver_ops functions set_cts_protect(),
set_preamble(), set_short_slot_time(), and set_ht_params(). These
belong into same set of operations as set_ap(), so there is no need
to maintain separate functions that just make the driver wrapper
more complex.

Since these have only been used with driver_nl80211.c, the driver_ops
can be removed immediately instead of maintaining backwards
compatibility period with the old functions.