mmc: sdhci-of-arasan: Use clock-frequency property to update clk_xin

If clock-frequency property is set and it is not the same as the current
clock rate of clk_xin(base clock frequency), set clk_xin to use the
provided clock rate.

Signed-off-by: Rashmi A <rashmi.a@intel.com>
Reviewed-by: Adrian Hunter <adrian.hunter@intel.com>
Tested-by: Sai Krishna Potthuri <lakshmi.sai.krishna.potthuri@xilinx.com>
Link: https://lore.kernel.org/r/20210603182242.25733-2-rashmi.a@intel.com


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