pinctrl: sh-pfc: r8a7794: Add tpu groups and function

This patch adds tpu groups and function to r8a7745/r8a7794.

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>