net: mscc: ocelot: add MAC table stream learn and lookup operations

ocelot_mact_learn_streamdata() can be used in VSC9959 to overwrite an
FDB entry with stream data. The stream data includes SFID and SSID which
can be used for PSFP and FRER set.

ocelot_mact_lookup() can be used to check if the given {DMAC, VID} FDB
entry is exist, and also can retrieve the DEST_IDX and entry type for
the FDB entry.

Signed-off-by: Xiaoliang Yang <xiaoliang.yang_1@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>