ixgbevf: skip null and permanent mac addresses

ixgbevf: skip null and permanent mac addresses

On a 82599 VF, the deletion of a dynamically added MAC address consists in
first flushing all added MAC addresses, then in adding again all remaining MAC
addresses.
For this purpose, the function ixgbevf_remove_mac_addr() parses the pool
of MAC addresses associated with a VF, and must skip the VF permanent MAC
address that is stored into it, as well as all NULL MAC addresses.

Signed-off-by: Ivan Boule <ivan.boule@6wind.com>
Acked-by: Thomas Monjalon <thomas.monjalon@6wind.com>