mlxsw: spectrum: Support IPIP underlay VRF migration

When a bound device of a tunnel netdevice changes VRF, the loopback RIF
that backs the tunnel needs to be updated and existing encapsulating
routes need to be refreshed.

Note that several tunnels can share the same bound device, in which case
all the impacted tunnels need to be updated.

Signed-off-by: Petr Machata <petrm@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>