Enable DM block and DM MMC support on DHCOM iMX6 PDK2.
Convert board code to match the DM support.
Signed-off-by: NMarek Vasut <marex@denx.de>
Cc: Fabio Estevam <fabio.estevam@nxp.com>
Cc: Ludwig Zenz <lzenz@dh-electronics.com>
Cc: Stefano Babic <sbabic@denx.de>