We're accidentally returning the wrong variable. "cmode" is
uninitialized at this point so it causes a static checker warning.
Fixes: 6335e9f2446b ("net: dsa: mv88e6xxx: mv88e6390X SERDES support") Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Reviewed-by: Andrew Lunn <andrew@lunn.ch> Signed-off-by: David S. Miller <davem@davemloft.net>