[SCSI] isci: overriding max_concurr_spinup oem parameter by max(oem, user)

Fixes bug where max_concurr_spinup oem parameter should be
overriden by max_concurr_spinup user parameter. Override should
happen only when max_concurr_spinup user parameter is specified
in command line (greater than 0). Also this fix shortens variables
representing max_conxurr_spinup for oem and user parameters.

Signed-off-by: Andrzej Jakowski <andrzej.jakowski@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>