clk: samsung: exynos7: add clocks for audio block

Add required clk support for I2S, PCM and SPDIF.

Signed-off-by: Padmavathi Venna <padma.v@samsung.com>
Reviewed-by: Vivek Gautam <gautam.vivek@samsung.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>