mmc: fsl_esdhc_imx: simplify esdhc_setup_data()

[ fsl_esdhc commit 7e48a028 ]

First, we need the waterlevel setting for PIO mode only. Secondy, both DMA
setup code is identical for both directions, except for the data pointer.
Thus, unify them.

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>