net: hns: fix return value check in __lb_other_process()

stable inclusion
from linux-4.19.167
commit 6928179970635accad665f34fbdaef3113b5cee0

--------------------------------

[ Upstream commit 5ede3ada ]

The function skb_copy() could return NULL, the return value
need to be checked.

Fixes: b5996f11 ("net: add Hisilicon Network Subsystem basic ethernet support")
Signed-off-by: Yunjian Wang <wangyunjian@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>

Signed-off-by: Aichun Li <liaichun@huawei.com>
reviewed-by: wangxiaopeng <wangxiaopeng7@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Cheng Jian <cj.chengjian@huawei.com>