Support WiGig SoftAP mode

WiGig softAP needed in standalone mode and FST modes.

In standalone mode, new API to start/stop WiGig softAP is added.

In FST mode, when FST enabled (persist.fst.rate.upgrade.en system property),
tether (including running dhcp server) over bonding driver instead of the
wifi driver.

Change-Id: If5d9555fddb321c38803dc77319243abfabe8c05