mmc: sdhci-of-arasan: Add sampling clock for a phy to use

There are some operations like setting the clock delays may need to have
two clocks, one for output path and one for input path. Adding input
path clock for some phys to use.

Signed-off-by: Manish Narani <manish.narani@xilinx.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>