mlxsw: spectrum: Reduce dependency between bridge and router code

Commit f40be47a

 ("mlxsw: spectrum_router: Do not force specific
configuration order") added a call from the routing code to the bridge
code in order to handle the case where VNI should be set on a FID
following the joining of the router port to the FID.

This is no longer required, as previous patches made VXLAN devices
explicitly take a reference on the FID and set VNI on it.

Therefore, remove the unnecessary call and simply have the RIF take a
reference on the FID without checking if VNI should also be set on it.

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