net/hns3: fix return value of setting VLAN offload

net/hns3: fix return value of setting VLAN offload

Currently, the '.vlan_offload_set' ops implementation function named
hns3vf_vlan_offload_set always return 0 in hns3 VF PMD driver.

This patch fixes it with the following modification in the function
named hns3vf_vlan_offload_set.
1. Avoid setting hardware configuration and return -EIO during resetting.
2. Add the return value detection process for calling internal static
   function named hns3vf_en_hw_strip_rxvtag.

Fixes: a5475d61fa34 ("net/hns3: support VF")
Cc: stable@dpdk.org
Signed-off-by: Chengwen Feng <fengchengwen@huawei.com>
Signed-off-by: Wei Hu (Xavier) <xavier.huwei@huawei.com>