Emmc DDR52 mode uses fixed delay, return earlier if
timing is MMC_TIMING_MMC_DDR52 in execute tuning function.
Signed-off-by: NZhoujie Wu <zjwu@marvell.com>
Acked-by: NAdrian Hunter <adrian.hunter@intel.com>
Signed-off-by: NUlf Hansson <ulf.hansson@linaro.org>