drivers: adc: stm32: use __maybe_unused

Replace conditional `ARG_UNUSED` with `__maybe_unused`. This is recommended
by coding style:
https://kernel.org/doc/html/latest/process/coding-style.html#conditional-compilation

Signed-off-by: Jeppe Odgaard <[email protected]>

Author: Jeppe Odgaard

drivers/adc/adc_stm32.c

@@ -1080,10 +1080,7 @@ static void adc_context_start_sampling(struct adc_context *ctx)
 		CONTAINER_OF(ctx, struct adc_stm32_data, ctx);
 	const struct device *dev = data->dev;
 	const struct adc_stm32_cfg *config = dev->config;
-	ADC_TypeDef *adc = config->base;
-
-	/* Remove warning for some series */
-	ARG_UNUSED(adc);
+	__maybe_unused ADC_TypeDef *adc = config->base;
 
 	data->repeat_buffer = data->buffer;
 
@@ -1154,7 +1151,7 @@ static void adc_context_on_complete(struct adc_context *ctx, int status)
 	struct adc_stm32_data *data =
 		CONTAINER_OF(ctx, struct adc_stm32_data, ctx);
 	const struct adc_stm32_cfg *config = data->dev->config;
-	ADC_TypeDef *adc = config->base;
+	__maybe_unused ADC_TypeDef *adc = config->base;
 
 	ARG_UNUSED(status);
 
@@ -1165,8 +1162,6 @@ static void adc_context_on_complete(struct adc_context *ctx, int status)
 #if defined(CONFIG_SOC_SERIES_STM32H7X) || defined(CONFIG_SOC_SERIES_STM32U5X)
 	/* Reset channel preselection register */
 	LL_ADC_SetChannelPreselection(adc, 0);
-#else
-	ARG_UNUSED(adc);
 #endif /* CONFIG_SOC_SERIES_STM32H7X || CONFIG_SOC_SERIES_STM32U5X */
 }
 
@@ -1237,7 +1232,7 @@ static int adc_stm32_sampling_time_setup(const struct device *dev, uint8_t id,
 	const struct adc_stm32_cfg *config =
 		(const struct adc_stm32_cfg *)dev->config;
 	ADC_TypeDef *adc = config->base;
-	struct adc_stm32_data *data = dev->data;
+	__maybe_unused struct adc_stm32_data *data = dev->data;
 
 	int acq_time_index;
 
@@ -1255,7 +1250,6 @@ static int adc_stm32_sampling_time_setup(const struct device *dev, uint8_t id,
 	switch (config->num_sampling_time_common_channels) {
 	case 0:
 #if ANY_NUM_COMMON_SAMPLING_TIME_CHANNELS_IS(0)
-		ARG_UNUSED(data);
 		LL_ADC_SetChannelSamplingTime(adc,
 					      __LL_ADC_DECIMAL_NB_TO_CHANNEL(id),
 					      (uint32_t)acq_time_index);
@@ -1491,11 +1485,9 @@ static int adc_stm32_set_clock(const struct device *dev)
 {
 	const struct adc_stm32_cfg *config = dev->config;
 	const struct device *const clk = DEVICE_DT_GET(STM32_CLOCK_CONTROL_NODE);
-	ADC_TypeDef *adc = config->base;
+	__maybe_unused ADC_TypeDef *adc = config->base;
 	int ret = 0;
 
-	ARG_UNUSED(adc); /* Necessary to avoid warnings on some series */
-
 	if (clock_control_on(clk,
 		(clock_control_subsys_t) &config->pclken[0]) != 0) {
 		return -EIO;
@@ -1560,11 +1552,9 @@ static int adc_stm32_init(const struct device *dev)
 	struct adc_stm32_data *data = dev->data;
 	const struct adc_stm32_cfg *config = dev->config;
 	const struct device *const clk = DEVICE_DT_GET(STM32_CLOCK_CONTROL_NODE);
-	ADC_TypeDef *adc = config->base;
+	__maybe_unused ADC_TypeDef *adc = config->base;
 	int err;
 
-	ARG_UNUSED(adc); /* Necessary to avoid warnings on some series */
-
 	LOG_DBG("Initializing %s", dev->name);
 
 	if (!device_is_ready(clk)) {