staging: wilc1000: handle get_station() ops callback in cfg80211 context

Refactor code to handle the get_station() callback from cfg80211
context. Provided different API's to fetch the station statistics
information in sync or async call. From cfg80211 get_station() ops
callback calls the sync version of API.

Signed-off-by: Ajay Singh <ajay.kathat@microchip.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>