mmc: sdhci-s3c: Support additional host capabilities

This patch adds support for additional host capabilities like SD/MMC
high speed, SDHCI bus width, etc.

Signed-off-by: Jeongbae Seo <jeongbae.seo@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
Signed-off-by: Chris Ball <cjb@laptop.org>