scsi: qla2xxx: Fix issue reported by static checker for qla2x00_els_dcmd2_sp_done()

This patch fixes following Smatch complaint:

drivers/scsi/qla2xxx/qla_iocb.c:2647 qla2x00_els_dcmd2_sp_done()
error: we previously assumed 'e' could be null (see line 2631)

Fixes: 8777e4314d39 ("scsi: qla2xxx: Migrate NVME N2N handling into state machine")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
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>

drivers/scsi/qla2xxx/qla_iocb.c

@@ -2642,6 +2642,7 @@ qla2x00_els_dcmd2_sp_done(void *ptr, int res)
 				    elsio->u.els_plogi.els_resp_pyld,
 				    elsio->u.els_plogi.els_resp_pyld_dma);
 			sp->free(sp);
+			return;
 		}
 		e->u.iosb.sp = sp;
 		qla2x00_post_work(vha, e);