pinctrl: sh-pfc: r8a77995: Add DU pins, groups and function

This patch adds DU pins, groups and function for the R8A77995 (D3) SoC.

Signed-off-by: Ulrich Hecht <ulrich.hecht+renesas@gmail.com>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>