dt-bindings: i2c: sh_mobile: Document r8a77961 support

Document support for the IIC controller in the Renesas R-Car M3-W+
(R8A77961) SoC.

No driver update is needed.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

Documentation/devicetree/bindings/i2c/renesas,iic.txt

@@ -17,6 +17,7 @@ Required properties:
 			- "renesas,iic-r8a7794" (R-Car E2)
 			- "renesas,iic-r8a7795" (R-Car H3)
 			- "renesas,iic-r8a7796" (R-Car M3-W)
+			- "renesas,iic-r8a77961" (R-Car M3-W+)
 			- "renesas,iic-r8a77965" (R-Car M3-N)
 			- "renesas,iic-r8a77990" (R-Car E3)
 			- "renesas,iic-sh73a0" (SH-Mobile AG5)