Writes larger than this will wrap to the same page. Reads larger than this are permitted, but why take chances.
Update i2c devices to just include the eeprom. Update dataflash chip select to be CS 1 (this doesn't work yet and needs changes to at91_spi and the spibus infrastructure). Fix typo in comment.
Initially identical to the Ethernut5, but will diverge shortly before I refactor...
