1. Provide the API to set/unset the spoof checking feature.
2. Add a function to periodically provide the count of found
   packets with spoof VF MAC address.
3. Prevent VF MAC address changing while the spoofchk of the VF is
   on unless the changing MAC address is issued from PF.

Signed-off-by: Weilin Chang <weilin.chang@cavium.com>
Signed-off-by: Felix Manlunas <felix.manlunas@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>