scsi: qla2xxx: Fix memory leak when sending I/O fails

On heavy loads, a memory leak of the srb_t structure is observed.  This
would make the qla2xxx_srbs cache gobble up memory.

Fixes: 219d27d7

 ("scsi: qla2xxx: Fix race conditions in the code for aborting SCSI commands")
Cc: stable@vger.kernel.org # 5.2
Link: https://lore.kernel.org/r/20191105150657.8092-7-hmadhani@marvell.com
Reviewed-by: Ewan D. Milne <emilne@redhat.com>
Signed-off-by: Arun Easi <aeasi@marvell.com>
Signed-off-by: Himanshu Madhani <hmadhani@marvell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>