ipoib: remove addrlen check for mc addresses

Finally this bit can be removed. Currently, after the bonding driver is
changed/fixed (32a806c194ea112cfab00f558482dd97bee5e44e net-next-2.6),
that's not possible for an addr with different length than dev->addr_len
to be present in list. Removing this check as in new mc_list there will be
no addrlen in the record.

Signed-off-by: Jiri Pirko <jpirko@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>