mmc: sdhci-of-esdhc: fix reference clock source selection

The bit ESDHC_PERIPHERAL_CLK_SEL to select using peripheral clock
or platform clock is not able to be reset by SDHCI_RESET_ALL.
So driver needs to initialize it as 1 or 0 once, to override the
different value which may be configured in bootloader.

Signed-off-by: Yangbo Lu <yangbo.lu@nxp.com>
Link: https://lore.kernel.org/r/20200927082304.9232-1-yangbo.lu@nxp.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>