bnx2x: add VF Multicast filters support

This patch adds the necessary support for configuring (and removing) multicast
filters to VFs.

Signed-off-by: Yuval Mintz <yuvalmin@broadcom.com>
Signed-off-by: Ariel Elior <ariele@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>