ARM: S5PC1xx: add platform helpers for SDHCI host controllers

Samsung S5PC100 has 3 SDHCI controllers compatible with the one known from
previous SoCs series. Add required platform setup and support code that
the devices can be used with sdhci-s3c driver.

Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>