sdhci-s3c: add missing remove function

System will crash sooner or later once the memory with the code of the
s3c-sdhci.ko module is reused for something else. I really have no idea
how the lack of remove function went unnoticed into the mainline code.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>