clk: samsung: register audio subsystem clocks using common clock framework

Audio subsystem is introduced in s5pv210 and exynos platforms.
This has seperate clock controller which can control i2s0 and
pcm0 clocks. This patch registers the audio subsystem clocks
with the common clock framework on Exynos family.

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