mmc: sdhci-pci: Add support for HS200 tuning mode on AMD, eMMC-4.5.1

This patch adds support for HS200 tuning mode on AMD eMMC-4.5.1

Reviewed-by: Sen, Pankaj <Pankaj.Sen@amd.com>
Reviewed-by: Shah, Nehal-bakulchandra <Nehal-bakulchandra.Shah@amd.com>
Reviewed-by: Agrawal, Nitesh-kumar <Nitesh-kumar.Agrawal@amd.com>
Signed-off-by: S-k, Shyam-sundar <Shyam-sundar.S-k@amd.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>