clk: stm32f4: Add I2S clock

This patch introduces I2S clock for stm32f4 soc.
The I2S clock could be derived from an external clock or from pll-i2s

Signed-off-by: Gabriel Fernandez <gabriel.fernandez@st.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
1 file changed