mlxsw: resources: Add multicast ERIF list entries resource

The multicast ERIF list entries resource indicates the number of entries
that can be put in one rigr2 register operation. While the register can
hold up to MLXSW_REG_RIGR2_MAX_ERIFS ( = 32) ERIF entries, the actual
number allowed by firmware is indicated with this resource.

Signed-off-by: Yotam Gigi <yotamg@mellanox.com>
Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>