arm64: dts: renesas: Add support for M3ULCB with R-Car M3e-2G

Add support for the Renesas R-Car Starter Kit Pro equipped with an R-Car
M3e-2G SiP.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://lore.kernel.org/r/c566dfa5f07605a467f8705c3a2f637ea445b1ff.1626708063.git.geert+renesas@glider.be