scsi: zfcp: remove unnecessary null pointer check before mempool_destroy

mempool_destroy has taken null pointer check into account. so remove the
redundant check.
Signed-off-by: zhong jiang <zhongjiang@huawei.com>
Acked-by: Benjamin Block <bblock@linux.ibm.com>
[maier@linux.ibm.com: depends on v4.3 4e3ca3e0 ("mm/mempool: allow NULL `pool' pointer in mempool_destroy()")]
Signed-off-by: Steffen Maier <maier@linux.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/s390/scsi/zfcp_aux.c

@@ -248,19 +248,12 @@ static int zfcp_allocate_low_mem_buffers(struct zfcp_adapter *adapter)
 
 static void zfcp_free_low_mem_buffers(struct zfcp_adapter *adapter)
 {
-	if (adapter->pool.erp_req)
 	mempool_destroy(adapter->pool.erp_req);
-	if (adapter->pool.scsi_req)
 	mempool_destroy(adapter->pool.scsi_req);
-	if (adapter->pool.scsi_abort)
 	mempool_destroy(adapter->pool.scsi_abort);
-	if (adapter->pool.qtcb_pool)
 	mempool_destroy(adapter->pool.qtcb_pool);
-	if (adapter->pool.status_read_req)
 	mempool_destroy(adapter->pool.status_read_req);
-	if (adapter->pool.sr_data)
 	mempool_destroy(adapter->pool.sr_data);
-	if (adapter->pool.gid_pn)
 	mempool_destroy(adapter->pool.gid_pn);
 }