MMC: S3C24XX: Add platform data for MMC/SD driver

This patch adds platform data support to the s3mci driver.  This allows
flexible board-specific configuration of set_power, card detect and read only
pins.

Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>