RGB666 has a pin assignment that differs from the other formats.

Fixes: 6b4de408 ("pinctrl: sh-pfc: r8a7795: Add VIN4, VIN5 pins, groups and functions")
Signed-off-by: Ulrich Hecht <ulrich.hecht+renesas@gmail.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>