clk: exynos5250: add clock ID for div_pcm0

There is no gate for the PCM clock input to the AudioSS block, so
the parent of sclk_pcm is div_pcm0.  Add a clock ID for it so that
we can reference it in device trees.

Signed-off-by: Andrew Bresticker <abrestic@chromium.org>
Reviewed-by: Tomasz Figa <t.figa@samsung.com>
Acked-by: Mike Turquette <mturquette@linaro.org>
Acked-by: Kukjin Kim <kgene.kim@samsung.com>
Signed-off-by: Tomasz Figa <t.figa@samsung.com>