pinctrl: sh-pfc: r8a7795: Add SDHI support

Add SDHI[0-3] pinmux support to r8a7795 SoC.

Signed-off-by: Takeshi Kihara <takeshi.kihara.df@renesas.com>
Signed-off-by: Dirk Behme <dirk.behme@gmail.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>