pinctrl: sh-pfc: r8a7795: Add DU parallel RGB output support

The H3 ES1.x and H3 ES2.0 have identical pinmuxing for the parallel RGB
output support.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>