net: thunderx: add multicast filter management support

The ThunderX NIC could be partitioned to up to 128 VFs and thus
represented to system. Each VF is mapped to pair BGX:LMAC, and each of VF
is configured by kernel individually. Eventually the bunch of VFs could be
mapped onto same pair BGX:LMAC and thus could cause several multicast
filtering configuration requests to LMAC with the same MAC addresses.

This commit is to add ThunderX NIC BGX filtering manipulation routines.

Signed-off-by: Vadim Lomovtsev <Vadim.Lomovtsev@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>