mmc: sdhci-sprd: Add PHY DLL delay configuration

Set the PHY DLL delay for each timing mode, which is used to sample the clock
accurately and make the clock more stable.

Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>