mmc: sdhci-esdhc-imx: remove the 100MHz limitation for Strobe DLL

mmc: sdhci-esdhc-imx: remove the 100MHz limitation for Strobe DLL

For some eMMC, after switch to HS400ES mode, it need to config the strobe
dll target dealy even if the clock is 50MHZ or 25MHz, otherwise will meet
CMD index/crc error when send CMD13 to check the switch status.

[    2.473915] IRQ status 0x000a8001
[    2.473934] mmc2: mmc_select_hs400es failed, error -84
[    2.473938] mmc2: error -84 whilst initialising MMC card

Signed-off-by: Haibo Chen <haibo.chen@nxp.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>