sh-pfc: r8a7740: Add SDHI and MMCIF pin groups and functions

Add pin groups for the first two SDHI interfaces and two alternative pin
groups for the MMCIF interface on the r8a7740 SoC.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>