ARM: dts: add Exynos audio subsystem clock controller node

Audio subsystem introduced in s5pv210 and exynos platforms
which has a internal clock controller. This patch adds a node
for the same on exynos5250.

Signed-off-by: Padmavathi Venna <padma.v@samsung.com>
Reviewed-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Reviewed-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>