pinctrl: sh-pfc: r8a77990: Add R8A774C0 PFC support

Renesas RZ/G2E (a.k.a. r8a774c0) is pin compatible with R-Car
E3 (a.k.a. r8a77990), however it doesn't have several automotive
specific peripherals. Add a r8a77990 specific pin groups/functions
along with common pin groups/functions for supporting both r8a77990
and r8a774c0 SoCs.

Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
Reviewed-by: Biju Das <biju.das@bp.renesas.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>