[SCSI] mpt2sas: Update the timing requirements for issuing a Hard Reset

Updated the mpt2sas driver code that issues hard reset to comply with the
timing requirements mentioned in MPI specifications rev V.

[jejb: checpatch fixes]
Signed-off-by: Sreekanth Reddy <Sreekanth.Reddy@lsi.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>