Support tuning for HS200 and SDR104. Now only 8QM/QXP are supported.
Some code is imported/modified from kernel sdhci-esdhc-imx.c.

On i.MX8QM LPDDR4 ARM2 board, emmc hs200:
Read speed: ~87MB/s
Write speed: ~67MB/s

Original data, emmc hs:
Read speed: ~43MB/s
Write speed: ~40.5MB/s

On i.MX8QM LPDDR4 ARM2 board, SDR104:
Read speed: ~44MB/s
Write speed: ~9.4MB/s

Original data, SD HS:
Read speed: ~22MB/s
Write speed: ~8.5MB/s

Signed-off-by: Peng Fan <peng.fan@nxp.com>