mmc: sdhci-esdhc-imx: Remove redundant code for manual tuning

For manual tuning method, already call esdhc_prepare_tuning() config the
necessary registers, so remove the redundant code in esdhc_writew_le() for
SDHCI_HOST_CONTROL2.

Signed-off-by: Haibo Chen <haibo.chen@nxp.com>
Link: https://lore.kernel.org/r/1629285415-7495-1-git-send-email-haibo.chen@nxp.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>