smsc75xx: let EEPROM determine GPIO/LED settings

This patch allows the GPIO/LED settings to be configured by the
EEPROM if present, and only sets the default values (LED outputs
for link/activity) when an EEPROM is not detected.

Signed-off-by: Steve Glendinning <steve.glendinning@shawell.net>
Signed-off-by: David S. Miller <davem@davemloft.net>