scsi: qla2xxx: Avoid that qla2x00_mem_free() crashes if called twice

Clear each pointer after having freed memory such that it becomes safe to
call qla2x00_mem_free() twice.

Cc: Himanshu Madhani <hmadhani@marvell.com>
Cc: Giridhar Malavali <gmalavali@marvell.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: Himanshu Madhani <hmadhani@marvell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/qla2xxx/qla_os.c

@@ -4715,6 +4715,8 @@ qla2x00_mem_free(struct qla_hw_data *ha)
 	if (ha->flt)
 		dma_free_coherent(&ha->pdev->dev, SFP_DEV_SIZE,
 		    ha->flt, ha->flt_dma);
+	ha->flt = NULL;
+	ha->flt_dma = 0;
 
 	if (ha->ms_iocb)
 		dma_pool_free(ha->s_dma_pool, ha->ms_iocb, ha->ms_iocb_dma);
@@ -4790,6 +4792,7 @@ qla2x00_mem_free(struct qla_hw_data *ha)
 
 	if (ha->dif_bundl_pool)
 		dma_pool_destroy(ha->dif_bundl_pool);
+	ha->dif_bundl_pool = NULL;
 
 	qlt_mem_free(ha);