mmc: sdhci-pltfm: Convert DT properties to generic device properties

Convert DT properties to generic device properties
so that drivers can get properties from DT or ACPI.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Tested-by: Srinath Mannam <srinath.mannam@broadcom.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>