wifi: introduce wifi_fst module

New wifi_fst module is responsible for:
1. insmod/rmmod of 2nd Wifi driver used for Fast Session Transfer (FST)
rate upgrade.
2. start/stop FST Manager service.

wifi_fst functionality is controlled by system property
persist.fst.rate.upgrade.en.

Existing module wifi.c calls into wifi_fst upon wifi_load/unload_driver
and upon start/stop supplicant

Change-Id: I8b4eddf26ab345b9e1e60e4850eaa081f8b89641
5 files changed