soc: renesas: Add Renesas R8A774B1 config option

Add configuration option for the RZ/G2N (R8A774B1) SoC.

Signed-off-by: Biju Das <biju.das@bp.renesas.com>
Link: https://lore.kernel.org/r/1567675844-19247-4-git-send-email-biju.das@bp.renesas.com


Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>