uboot-phytec

arm: imx7s-warp: Convert to DM MMC initialization

Converts from fixed initialization of MMC to DM initialization of MMC.

Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Cc: Albert Aribaud <albert.u.boot@aribaud.net>
Cc: Peng Fan <peng.fan@nxp.com>
Cc: Fabio Estevam <fabio.estevam@nxp.com>
Cc: Stefano Babic <sbabic@denx.de>