mdio: Check MDIO_STAT1_FAULT in mdio45_links_ok()

Some PHYs will report that the link is up even though there is a fault
condition.  Therefore, check the fault flag too.  We must also read
STAT2 to reset this flag.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>