IB/hns: Use kmalloc_array() in hns_roce_cmd_use_events()

* A multiplication for the size determination of a memory allocation
  indicated that an array data structure should be processed.
  Thus use the corresponding function "kmalloc_array".

  This issue was detected by using the Coccinelle software.

* Replace the specification of a data structure by a pointer dereference
  to make the corresponding size determination a bit safer according to
  the Linux coding style convention.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/hns/hns_roce_cmd.c

@@ -299,9 +299,9 @@ int hns_roce_cmd_use_events(struct hns_roce_dev *hr_dev)
 	struct hns_roce_cmdq *hr_cmd = &hr_dev->cmd;
 	int i;
 
-	hr_cmd->context = kmalloc(hr_cmd->max_cmds *
-				  sizeof(struct hns_roce_cmd_context),
-				  GFP_KERNEL);
+	hr_cmd->context = kmalloc_array(hr_cmd->max_cmds,
+					sizeof(*hr_cmd->context),
+					GFP_KERNEL);
 	if (!hr_cmd->context)
 		return -ENOMEM;