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>