trats: fdt: disable unused DW MMC

This device uses SDHCI driver, for eMMC and SD cards.
Trying bind the DW MMC driver with fdt node without all
required properties, causes printing an error.

This commit disables the DW MMC node.

Tested-on: Trats

Signed-off-by: Przemyslaw Marczak <p.marczak@samsung.com>
Cc: Łukasz Majewski <l.majewski@samsung.com>
Cc: Minkyu Kang <mk7.kang@samsung.com>