net: dsa: bcm_sf2: Call setup during switch resume

There is no reason to open code what the switch setup function does, in
fact, because we just issued a switch reset, we would make all the
register get their default values, including for instance, having unused
port be enabled again and wasting power and leading to an inappropriate
switch core clock being selected.

Fixes: 8cfa9498 ("net: dsa: bcm_sf2: add suspend/resume callbacks")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>