net: dsa: update DSA drivers to use ds_to_priv

Use the helper function to retrieve the driver private context instead of
using (void *)(ds + 1).

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

diff --cc drivers/net/dsa/mv88e6123_61_65.c
Simple merge

diff --cc drivers/net/dsa/mv88e6131.c
Simple merge

diff --cc drivers/net/dsa/mv88e6xxx.c
Simple merge