ex_read_eeprom
val = ex_read_eeprom(sc, EEPROM_OEM_ADDR0);
val = ex_read_eeprom(sc, EEPROM_OEM_ADDR1);
val = ex_read_eeprom(sc, EEPROM_OEM_ADDR2);
uint16_t ex_read_eeprom(struct ex_softc *, int);