arm64: dts: renesas: Add support for Salvator-XS with R-Car M3Ne-2G

Add support for the Renesas Salvator-X 2nd version development board
equipped with an R-Car M3Ne-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/efced5c7ff71b0a0ae359be12112e0d4dfb21a72.1628766192.git.geert+renesas@glider.be