ARM: dts: genmai: Correct primary compatible value for eeprom

The Renesas part number of the two-wire serial interface EEPROM is not
24C128, but R1EX24128ASA00A.

Hence change its primary compatible value to "renesas,r1ex24128".

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>