hinic: Use kmemdup instead of kzalloc and memcpy

Fixes coccicheck warnings:

 drivers/net/ethernet/huawei/hinic/hinic_hw_mbox.c:452:17-24: WARNING opportunity for kmemdup
 drivers/net/ethernet/huawei/hinic/hinic_hw_mbox.c:458:23-30: WARNING opportunity for kmemdup
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Zou Wei <zou_wei@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/huawei/hinic/hinic_hw_mbox.c

@@ -449,18 +449,15 @@ static void recv_mbox_handler(struct hinic_mbox_func_to_func *func_to_func,
 		return;
 	}
 
-	rcv_mbox_temp = kzalloc(sizeof(*rcv_mbox_temp), GFP_KERNEL);
+	rcv_mbox_temp = kmemdup(recv_mbox, sizeof(*rcv_mbox_temp), GFP_KERNEL);
 	if (!rcv_mbox_temp)
 		return;
 
-	memcpy(rcv_mbox_temp, recv_mbox, sizeof(*rcv_mbox_temp));
-
-	rcv_mbox_temp->mbox = kzalloc(MBOX_MAX_BUF_SZ, GFP_KERNEL);
+	rcv_mbox_temp->mbox = kmemdup(recv_mbox->mbox, MBOX_MAX_BUF_SZ,
+				      GFP_KERNEL);
 	if (!rcv_mbox_temp->mbox)
 		goto err_alloc_rcv_mbox_msg;
 
-	memcpy(rcv_mbox_temp->mbox, recv_mbox->mbox, MBOX_MAX_BUF_SZ);
-
 	rcv_mbox_temp->buf_out = kzalloc(MBOX_MAX_BUF_SZ, GFP_KERNEL);
 	if (!rcv_mbox_temp->buf_out)
 		goto err_alloc_rcv_mbox_buf;