cifs: convert to use be32_add_cpu()

Convert cpu_to_be32(be32_to_cpu(E1) + E2) to use be32_add_cpu().

Signed-off-by: Qinglang Miao <miaoqinglang@huawei.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
diff --git a/fs/cifs/sess.c b/fs/cifs/sess.c
index 6708ab0..69cd585 100644
--- a/fs/cifs/sess.c
+++ b/fs/cifs/sess.c
@@ -938,8 +938,7 @@ sess_sendreceive(struct sess_data *sess_data)
 	struct kvec rsp_iov = { NULL, 0 };
 
 	count = sess_data->iov[1].iov_len + sess_data->iov[2].iov_len;
-	smb_buf->smb_buf_length =
-		cpu_to_be32(be32_to_cpu(smb_buf->smb_buf_length) + count);
+	be32_add_cpu(&smb_buf->smb_buf_length, count);
 	put_bcc(count, smb_buf);
 
 	rc = SendReceive2(sess_data->xid, sess_data->ses,