4819 fix mpt_sas command timeout handling
Reviewed by: Hans Rosenfeld <hans.rosenfeld@nexenta.com>
Reviewed by: Josef 'Jeff' Sipek <jeffpc@josefsipek.net>
Reviewed by: Keith Wesolowski <keith.wesolowski@joyent.com>
Approved by: Dan McDonald <danmcd@omniti.com>