cd->sw_addr is used as a MDIO bus address, which cannot exceed
PHY_MAX_ADDR (32), our check was off-by-one.
Fixes: 5e95329b70 ("dsa: add device tree bindings to register DSA switches")
Signed-off-by: Florian Fainelli <[email protected]>
Signed-off-by: David S. Miller <[email protected]>