mlxsw: spectrum: Initialize ports at the end of init sequence

During ports initialization a net device is registered for each
available port, which implies the port is usable. However, a port is
only usable after the different parts of the device (e.g. flooding,
buffers) are initialized. This is especially important now, when we must
initialize the router before the ports, as otherwise the device can't be
initialized.

Solve that by initializing the switch ports at the end of init sequence.

Also, remove an unnecessary warning about port up/down events, which
would otherwise be invoked whenever removing the driver, as ports are
removed before unregistering the listener for these events.

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