ARM: dts: replace number by macro in clock binding for exynos5250

Phy and sss module device node missed clock macro.
This patch replace magic number with macros in clock
binding for exynos5250.

Signed-off-by: Beomho Seo <beomho.seo@samsung.com>
Reviewed-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>