arm: rmobile: gose: Add support SDHI

Gose board has three SDHI port.
This adds GPIO configuration and initialization function of SDHI, and
enables MMC command.

Signed-off-by: Nobuhiro Iwamatsu <nobuhiro.iwamatsu.yj@renesas.com>
Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>