Add support for pin and gpio controller driver for RZ/G2L SoC.

Based on a patch in the BSP by Hien Huynh <hien.huynh.px@renesas.com>.
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Biju Das <biju.das.jz@bp.renesas.com>
Link: https://lore.kernel.org/r/20210727112328.18809-3-prabhakar.mahadev-lad.rj@bp.renesas.comSigned-off-by: Geert Uytterhoeven <geert+renesas@glider.be>