scsi: mpt3sas: simplify mpt3sas_scsi_issue_tm()

Move the check for outstanding commands out of the function allowing us
to simplify the overall code.

Signed-off-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Suganath Prabu S <suganath-prabu.subramani@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>