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

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?

Open the linked eeprom_clear.ino example and inspect line 30, then compare the EEPROM write and update APIs in the Arduino AVR core. Done means the example uses the requested API and still builds as an Arduino example; no test file is mentioned in the issue.

Written by the indexing model from the issue text.