Device model for standard SD Host Controller Interface (SDHCI) compliant with
version 2.00 of SD association specification.

Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Signed-off-by: Igor Mitsyanko <i.mitsyanko@samsung.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>