SoC: stm32: i2s: manage clock power

SoC: stm32: i2s: manage clock power

Kernel clock management:
Enable/disable I2S kernel clock on audio stream startup/shutdown.

Peripheral clock management:
Manage I2S peripheral clock power through regmap services.

Signed-off-by: Olivier Moysan <olivier.moysan@st.com>
Signed-off-by: Mark Brown <broonie@kernel.org>