This commit merges the driver_ops structures and implementations from
hostapd/driver*.[ch] into src/drivers. This is only an initial step and
there is room for number of cleanups to share code between the hostapd
and wpa_supplicant parts of the wrappers to avoid unnecessary source
code duplication.
Don't cast pointers to int in definitions of PRISM2_HOSTAPD_RID_HDR_LEN
and PRISM2_HOSTAPD_GENERIC_ELEMENT_HDR_LEN. Use size_t instead. That's
actually what the code needs.
