net: dsa: mv88e6xxx: check errors in mv88e6352_serdes_irq_link

net: dsa: mv88e6xxx: check errors in mv88e6352_serdes_irq_link

The mv88e6352_serdes_irq_link helper is not checking for any error that
may occur during hardware accesses. Worst, the "up" boolean is set from
the potentially unused "status" variable, if read operations failed.

As done in mv88e6390_serdes_irq_link_sgmii, return right away and do
not call dsa_port_phylink_mac_change if an error occurred.

Signed-off-by: Vivien Didelot <vivien.didelot@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>