mlxsw: Add extack to mlxsw_sp_nve_ops.fdb_replay

A follow-up patch will extend vxlan_fdb_replay() with an extack
argument. Extend the fdb_replay callback in mlxsw likewise so that the
argument is ready for the vxlan conversion.

Signed-off-by: Petr Machata <petrm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>