ndo_set_vf_mac() call may be issued for a mac-addr that is already
active on a VF. If so, silently ignore the request.

Signed-off-by: Vasundhara Volam <vasundhara.volam@emulex.com>
Signed-off-by: Sathya Perla <sathya.perla@emulex.com>
Signed-off-by: David S. Miller <davem@davemloft.net>