clk: exynos-audss: Staticize exynos_audss_clk_init

exynos_audss_clk_init() is used only in this file. Make it
static.

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Acked-by: Kukjin Kim <kgene.kim@samsung.com>
Reviewed-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>