scsi: qla2xxx: Fix memory leak for allocating abort IOCB

In the case of IOCB QFull, Initiator code can leave behind a stale pointer
to an SRB structure on the outstanding command array.

Fixes: 82de802a

 ("scsi: qla2xxx: Preparation for Target MQ.")
Cc: stable@vger.kernel.org #v4.16+
Signed-off-by: Quinn Tran <quinn.tran@cavium.com>
Signed-off-by: Himanshu Madhani <himanshu.madhani@cavium.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>