ARM: dts: correct the dw-mshc timing properties as per binding

As per the current exynos-dw-mshc bindings, dw-mshc-sdr-timing and
dw-mshc-ddr-timing properties are having only two cells, these properties
are wrongly set for exynos5250 based cros5250 and smdk5250 platfroms. This
patch corrects above timing propreties for above platfroms

Signed-off-by: Alim Akhtar <alim.akhtar@samsung.com>
Tested-by: Doug Anderson <dianders@chromium.org>
Acked-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>