be2net: Add multicast filter capability for Lancer

Lancer requires multicast capability flag set during IFACE_CREATE
for adding multicast filters.

Signed-off-by: Padmanabh Ratnakar <padmanabh.ratnakar@emulex.com>
Signed-off-by: Sathya Perla <sathya.perla@emulex.com>
Signed-off-by: Subramanian Seetharaman <subbu.seetharaman@emulex.com>
Signed-off-by: David S. Miller <davem@davemloft.net>