Revert Nexenta mpt_sas changes

This reverts the following commits:

  f53415151c96fb56f7af0703c7195924ae1aaa89
  cc25253c4d16fdad4398b24dd7034f94f7115104
  45e1300f0654325af4f25ee7539893b08b3cbf09
  aa6cdd4507ded3fd8ba29ee2e02a0348f1c3abad
  277e2bc6f962f2d6700726612cb7da6aba552c21