ARM: dts: da850-lego-ev3: use a correct fallback for at24 compatible

We now require all at24 users to use the "atmel,<model>" fallback in
device tree for different manufacturers.

Reviewed-by: David Lechner <david@lechnology.com>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>