net: hns3: split out hclgevf_cmd_send()

hclgevf_cmd_send() is bloated, so split it into separate
functions for readability and maintainability.

Signed-off-by: Yufeng Mo <moyufeng@huawei.com>
Signed-off-by: Huazhong Tan <tanhuazhong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>