pinctrl: sh-pfc: r8a7796: Add SDHI pins, groups and functions

This patch adds SDHI pins, groups and functions to R8A7796 SoC.

Signed-off-by: Takeshi Kihara <takeshi.kihara.df@renesas.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>