uboot-imx

mmc: hi6220_dw_mmc: Add hi6220 glue code for dw_mmc controller.

This patch adds the glue code for hi6220 SoC which has 2x synopsis
dw_mmc controllers. This will be used by the hikey board support
in subsequent patches.

Signed-off-by: Peter Griffin <peter.griffin@linaro.org>
Reviewed-by: Simon Glass <sjg@chromium.org>