ARM: dts: uniphier: Add one more generic compatible string for I2C EEPROM

Commit 73f9de0c

 ("ARM: dts: uniphier: Add generic compatible string
for I2C EEPROM") did not touch this node.

Add the compatible string prefixed "atmel," so that this matches to the
OF table.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>