Marvell controller requires 1.8V bit in UHS control register 2
be set when doing UHS.  eMMC does not require 1.8V for DDR.
add platform code to handle this.
Signed-off-by: NPhilip Rakity <prakity@marvell.com>
Reviewed-by: NArindam Nath <arindam.nath@amd.com>
Signed-off-by: NChris Ball <cjb@laptop.org>