EAPOL auth: Move radius_cui/identity freeing to eapol_auth_free()
These can get allocated within eapol_auth_alloc(), so it is more logical
to free them in eapol_auth_free() instead of ieee802_1x_free_station()
that ends up calling eapol_auth_free().
Signed-off-by: Jouni Malinen <j@w1.fi>