dt-bindings: at24: add Renesas R1EX24128

Document the compatible value for the Renesas R1EX24128ASAS0A two-wire
serial interface EEPROM, so it can be used in DTS files without causing
checkpatch warnings.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>

Documentation/devicetree/bindings/eeprom/at24.txt

@@ -49,6 +49,7 @@ Required properties:
 
                 "nxp,se97b" - the fallback is "atmel,24c02",
                 "renesas,r1ex24002" - the fallback is "atmel,24c02"
+                "renesas,r1ex24128" - the fallback is "atmel,24c128"
                 "rohm,br24t01" - the fallback is "atmel,24c01"
 
   - reg: The I2C address of the EEPROM.