ASoC: stm32: i2s: fix registers declaration in regmap

- Declare SR as volatile, as it is changed by hardware.
- Remove TXDR from readable and volatile register list,
as it is intended for write accesses only.
Signed-off-by: Olivier Moysan <olivier.moysan@st.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/stm/stm32_i2s.c

@@ -281,7 +281,6 @@ static bool stm32_i2s_readable_reg(struct device *dev, unsigned int reg)
 	case STM32_I2S_CFG2_REG:
 	case STM32_I2S_IER_REG:
 	case STM32_I2S_SR_REG:
-	case STM32_I2S_TXDR_REG:
 	case STM32_I2S_RXDR_REG:
 	case STM32_I2S_CGFR_REG:
 		return true;
@@ -293,7 +292,7 @@ static bool stm32_i2s_readable_reg(struct device *dev, unsigned int reg)
 static bool stm32_i2s_volatile_reg(struct device *dev, unsigned int reg)
 {
 	switch (reg) {
-	case STM32_I2S_TXDR_REG:
+	case STM32_I2S_SR_REG:
 	case STM32_I2S_RXDR_REG:
 		return true;
 	default: