arm: rmobile: koelsch: Add support SDHI

Koelsch 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>
diff --git a/configs/koelsch_defconfig b/configs/koelsch_defconfig
index fd7a558..b1e3529 100644
--- a/configs/koelsch_defconfig
+++ b/configs/koelsch_defconfig
@@ -3,3 +3,4 @@
 CONFIG_TARGET_KOELSCH=y
 CONFIG_DM=y
 CONFIG_DM_SERIAL=y
+CONFIG_SH_SDHI=y