net: dsa: first set up shared ports, then non-shared ports

After commit a57d8c21

 ("net: dsa: flush switchdev workqueue before
tearing down CPU/DSA ports"), the port setup and teardown procedure
became asymmetric.

The fact of the matter is that user ports need the shared ports to be up
before they can be used for CPU-initiated termination. And since we
register net devices for the user ports, those won't be functional until
we also call the setup for the shared (CPU, DSA) ports. But we may do
that later, depending on the port numbering scheme of the hardware we
are dealing with.

It just makes sense that all shared ports are brought up before any user
port is. I can't pinpoint any issue due to the current behavior, but
let's change it nonetheless, for consistency's sake.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>