Unified netd patch
[*]Fix WPA2 AP
   Reference:
   http://server.cas-online.nl:8181/#/c/835/1/SoftapController.cpp,unified
[*]system/netd: fix hotspot using legacy hostapd binaries
   Two changes:
   1. Modify SoftapController::startDriver function to ensure that the
   wireless interface is initialized before attempting to start the interface.
   This may only be needed for the ar6000 driver (which needs the interface
   up to be able to function).
   2. Add a new BoardConfig option to improve compatibility with older
   (v0.6 or earlier) hostapd binaries. Activate with:
   BOARD_HAVE_LEGACY_HOSTAPD := true
[*]SoftAP: allow a hostapd service and handle the wifi channel
   (using command parameters, or the new property "wifi.ap.channel")