scsi: qla2xxx: Fix warning for missing error code

Fix smatch-reported warning message:

drivers/scsi/qla2xxx/qla_target.c:3324 qlt_xmit_response() warn: missing error
code 'res'

Link: https://lore.kernel.org/r/20220110050218.3958-12-njavali@marvell.com
Fixes: 4a8f7101

 ("scsi: qla2xxx: Fix unmap of already freed sgl")
Cc: stable@vger.kernel.org
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Nilesh Javali <njavali@marvell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>