The wps_context data is now managed at wpa_supplicant, not EAP-WSC. This
makes wpa_supplicant design for WPS match with hostapd one and also
makes it easier configure whatever parameters and callbacks are needed
for WPS.
This cleans up the internal interface between different modules and is
the first step in getting wpa_supplicant design closer to hostapd as far
as WPS is concerned.