[SCSI] mpt2sas: fix firmware failure with wrong task attribute

When SCSI command is received with task attribute not set, set it to SIMPLE.
Previously it is set to untagged. This causes the firmware to fail the commands.

Signed-off-by: Sreekanth Reddy <Sreekanth.Reddy@lsi.com>
Cc: stable@vger.kernel.org
Signed-off-by: James Bottomley <JBottomley@Parallels.com>