net: hns3: Add HNS3 VF driver to kernel build framework

This patch introduces the new Makefiles and updates existing
Makefiles required to build the HNS3 Virtual Function driver.
This also updates the Kconfig for introduction of new menuconfig
entries related to VF driver.

Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
Signed-off-by: lipeng <lipeng321@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>