ARM: mvebu: Use standard MMC binding for all users of mvsdio

In order to prepare the switch to the standard MMC device tree parser
for mvsdio, adapt all current uses of mvsdio in the dts files to the
standard format.

Signed-off-by: Simon Baatz <gmbnomis@gmail.com>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>