pinctrl: sh-pfc: r8a77990: Add DRIF pins, groups and functions

This patch adds DRIF{0,1,2,3} pins, groups and functions to the R8A77990
SoC.

Signed-off-by: Takeshi Kihara <takeshi.kihara.df@renesas.com>
Signed-off-by: Yoshihiro Kaneko <ykaneko0929@gmail.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>