iscsi-target: Use kcalloc() in iscsit_allocate_iovecs()

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

  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: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/target/iscsi/iscsi_target.c

@@ -984,8 +984,7 @@ static int iscsit_allocate_iovecs(struct iscsi_cmd *cmd)
 	u32 iov_count = max(1UL, DIV_ROUND_UP(cmd->se_cmd.data_length, PAGE_SIZE));
 
 	iov_count += ISCSI_IOV_DATA_BUFFER;
-
-	cmd->iov_data = kzalloc(iov_count * sizeof(struct kvec), GFP_KERNEL);
+	cmd->iov_data = kcalloc(iov_count, sizeof(*cmd->iov_data), GFP_KERNEL);
 	if (!cmd->iov_data) {
 		pr_err("Unable to allocate cmd->iov_data\n");
 		return -ENOMEM;