qed*: Allow unicast filtering

Apparently qede fails to set IFF_UNICAST_FLT, and as a result is not
actually performing unicast MAC filtering.
While we're at it - relax a hard-coded limitation that limits each
interface into using at most 15 unicast MAC addresses before turning
promiscuous. Instead utilize the HW resources to their limit.

Signed-off-by: Yuval Mintz <Yuval.Mintz@caviumnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>