arm64: dts: renesas: r8a77961: Add I2C nodes

Add device nodes for the I2C and IIC Controllers on the Renesas R-Car
M3-W+ (r8a77961) SoC, including DMA properties linking them to the DMA
controllers.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Eugeniu Rosca <erosca@de.adit-jv.com>
Tested-by: Eugeniu Rosca <erosca@de.adit-jv.com>
Link: https://lore.kernel.org/r/20191216124740.16647-6-geert+renesas@glider.be