staging: wfx: implement the rest of mac80211 API

Finish to fill struct ieee80211_ops with necessary callbacks. Driver is
now ready to be registered to mac80211.

Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20190919142527.31797-21-Jerome.Pouiller@silabs.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>