arm64: dts: renesas: Add Renesas R8A779M3 SoC support

Add support for the Renesas R-Car M3e-2G (R8A779M3) SoC, which is a
different grading of the R-Car M3-W+ (R8A77961) SoC.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Link: https://lore.kernel.org/r/bbb3131ccdd615b59c46297c2ea37147c7ff84e1.1626708063.git.geert+renesas@glider.be