uboot-phytec

colibri_imx6: unify sd/mmc drive strenght with linux kernel settings

In the linux device tree we use 40Ohm drive strenght. So use the same
value in U-Boot.

Signed-off-by: Max Krummenacher <max.krummenacher@toradex.com>
Acked-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>