mmc: s3cmci: port DMA code to dmaengine API

Utilise new s3c24xx-dma dmaengine driver for DMA ops.

Signed-off-by: Vasily Khoruzhick <anarsoul@gmail.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>