ASoC: stm32: Add I2S driver

Add I2S ASoC driver for STM32.
This version of the driver supports only
exclusive playback and capture interface.
Signed-off-by: olivier moysan <olivier.moysan@st.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/stm/Kconfig

@@ -5,4 +5,4 @@ menuconfig SND_SOC_STM32
 	select SND_SOC_GENERIC_DMAENGINE_PCM
 	select REGMAP_MMIO
 	help
-	  Say Y if you want to enable ASoC-support for STM32
+	  Say Y if you want to enable ASoC support for STM32

sound/soc/stm/Makefile

@@ -4,3 +4,7 @@ obj-$(CONFIG_SND_SOC_STM32) += snd-soc-stm32-sai-sub.o
 
 snd-soc-stm32-sai-objs := stm32_sai.o
 obj-$(CONFIG_SND_SOC_STM32) += snd-soc-stm32-sai.o
+
+# I2S
+snd-soc-stm32-i2s-objs := stm32_i2s.o
+obj-$(CONFIG_SND_SOC_STM32) += snd-soc-stm32-i2s.o