After some careful code analysis, be a little more careful

	After some careful code analysis, be a little more careful
	about freeing the memory.  There have been reports of memory
	leaks...

	sub-types do:  type.data = malloc()
	eap_wireformat does: free(type.data)

	BUT eap_packet_free doesn't free type.data, even if it's not
	NULL.  This may be a surprise.  There may also be code paths
	where the memory gets allocated WITHOUT it being packed into
	a packet.  So we fix the code here to be a little more careful