gpio: rcar: Add R8A7743 (RZ/G1M) support

Renesas RZ/G1M (R8A7743) SoC GPIO blocks are identical to the R-Car Gen2
family. Add support for its GPIO controllers.

Signed-off-by: Biju Das <biju.das@bp.renesas.com>
Reviewed-by: Chris Paterson <chris.paterson2@renesas.com>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>