i2c: rcar: Add compatible support for r8a77990 (R-Car E3)

This patch adds compatible string support for the Renesas R-Car E3
(r8a77990) SoC.

Signed-off-by: Hiromitsu Yamasaki <hiromitsu.yamasaki.ym@renesas.com>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

Documentation/devicetree/bindings/i2c/i2c-rcar.txt

@@ -16,6 +16,7 @@ Required properties:
 	"renesas,i2c-r8a77965" if the device is a part of a R8A77965 SoC.
 	"renesas,i2c-r8a77970" if the device is a part of a R8A77970 SoC.
 	"renesas,i2c-r8a77980" if the device is a part of a R8A77980 SoC.
+	"renesas,i2c-r8a77990" if the device is a part of a R8A77990 SoC.
 	"renesas,i2c-r8a77995" if the device is a part of a R8A77995 SoC.
 	"renesas,rcar-gen1-i2c" for a generic R-Car Gen1 compatible device.
 	"renesas,rcar-gen2-i2c" for a generic R-Car Gen2 or RZ/G1 compatible