serial: sh-sci: Add R-Car Gen5 support

Add "rcar-gen5-scif" compatible string for R-Car Gen5 support.

Signed-off-by: Nghia Nguyen <nghia.nguyen.jg@renesas.com>
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/87cyahdgfu.wl-kuninori.morimoto.gx@renesas.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>