Commit 61dccf73 (dts: mvebu: a80x0: Enable SD/eMMC interfaces) added
a redundant DT node for SD card slot. Drop it.

Cc: Konstantin Porotchkin <kostap@marvell.com>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Stefan Roese <sr@denx.de>