mmc: fsl_esdhc_imx: fix watermark level in dma

Seems that we need the waterlevel setting not only for PIO mode as
without this at least the i.MX 8M Mini won't boot anymore when being
written by such a U-Boot. Corruption has also been observed both on
the i.MX 6 as well as i.MX 8M Mini when using ums on the eMMC. Fix
this by setting the watermark level again regardless of whether in
DMA or PIO mode.

Fixes: 41c6a22f ("mmc: fsl_esdhc_imx: simplify esdhc_setup_data()")
Signed-off-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Tested-by: Fabio Estevam <festevam@gmail.com>