sfc: Insert multicast filters as well as mismatch filters in promiscuous mode

If a function is in promiscuous mode and another function has a broadcast or
 multicast filter inserted, the function in promiscuous mode won't see that
 broadcast or multicast traffic.
Most notably this breaks broadcast, which means ARP doesn't work. Less
 show-stoppingly, a function listening on a multicast address that's also in
 promiscuous mode will not see that multicast traffic if another function is
 also listening on that multicast address.

Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>