mmc: fsl_esdhc_imx: use dma-mapping API

[ fsl_esdhc commit b1ba1460 ]

Use the dma_{map,unmap}_single() calls. These will take care of the
flushing and invalidation of caches.

Signed-off-by: Michael Walle <michael@walle.cc>
Signed-off-by: Sean Anderson <sean.anderson@seco.com>
Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>