eeprom_clear.ino should use update() rather than write()

[NicoHood]

https://github.com/arduino/Arduino/blob/master/hardware/arduino/avr/libraries/EEPROM/examples/eeprom_clear/eeprom_clear.ino#L30

I think the message is clear, the fix simple. Anything against that?

[rkost]

Looks good to me