mmc: exynos_dw_mmc: Read upstream SDR timing properties

mmc: exynos_dw_mmc: Read upstream SDR timing properties

The obsolete "samsung,timing" dts property is now split into
"samsung,dw-mshc-ciu-div" (for holding the internal DW MMC divider
value) and "samsung,dw-mshc-sdr-timing" (for actual timing values) in
upstream Linux kernel. Rework the driver to make use of new properties
instead of the old one. All affected dts files were already updated
accordingly.

No functional change.

Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>