mmc: sdhci-esdhc-imx: simplify the auto tuning logic

Clear auto tuning bit when reset tuning, and enable auto tuning
only after tuning done successfully for both standard tuning and
manual tuning.

Signed-off-by: Haibo Chen <haibo.chen@nxp.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Link: https://lore.kernel.org/r/20221223025022.1893102-2-haibo.chen@nxp.com


Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>