qtnfmac: configure and start AP interface with a single command

Current logic artificially divides "start AP" procedure into three
stages:
- generic interface configuration (security, channel etc)
- IE's processing
- enable AP mode on interface

This separation would not allow to do a proper device configuration as
first stage needs to use information from IEs that are processed on
a second stage. Which means first and second stages have to be meged.
In that case there is no point anymore to keep third stage either, so
merge all three into a single command.

This new command carries all the same info as contained in
"struct cfg80211_ap_settings".

Signed-off-by: Igor Mitsyanko <igor.mitsyanko.os@quantenna.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>