net: dsa: switch to devm_ calls and remove kfree calls

Now the kfree calls exists in the the remove functions, remove them in all
places except the of_probe functions and replace allocation calls
with their devm_ counterparts.

Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: David S. Miller <davem@davemloft.net>