sdhci: enable multiblock transfers in sdhci-s3c

Wifi over SDIO doesn't work correctly without multiblock, so enable this.
This patch depends on the following patches:

Signed-off-by: Maurus Cuelenaere <mcuelenaere@gmail.com>
Cc: Thomas Abraham <thomas.ab@samsung.com>
Cc: Ben Dooks <ben-linux@fluff.org>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>