mifare: Correct memory leaks

mifare: Correct memory leaks

There were some memory leaks:
	* in some reading and writing callback functions,
	  in case sending command failed (e.g. after
	  failed authorisation), cookie wasn't released,
	* after checking presence global cookie wasn't released,
	* while processing MADs before writing, new data was
          allocated (although there was no need for this) and so
          the old one was lost.