If users set unicast mac address for VFs by PF, they need to guarantee all
VFs' address is different. This patch removes the check mac address exist
of VFs, for usrs can refresh mac addresses of all VFs directly without
need to modify the exist mac address to other value firstly.

Fixes: 8e6de441 ("net: hns3: add support for configuring VF MAC from the host")
Signed-off-by: NGuangbin Huang <huangguangbin2@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>