IIO: ADC: stm32_dfsdm_stop_filter() can be static

Fixes: e2e6771c ("IIO: ADC: add STM32 DFSDM sigma delta ADC support")
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Acked-by: Arnaud Pouliquen <arnaud.pouliquen@st.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/iio/adc/stm32-dfsdm-adc.c

@@ -254,7 +254,7 @@ static int stm32_dfsdm_start_filter(struct stm32_dfsdm *dfsdm,
 				  DFSDM_CR1_RSWSTART(1));
 }
 
-void stm32_dfsdm_stop_filter(struct stm32_dfsdm *dfsdm, unsigned int fl_id)
+static void stm32_dfsdm_stop_filter(struct stm32_dfsdm *dfsdm, unsigned int fl_id)
 {
 	/* Disable conversion */
 	regmap_update_bits(dfsdm->regmap, DFSDM_CR1(fl_id),
@@ -296,7 +296,7 @@ static int stm32_dfsdm_filter_configure(struct stm32_dfsdm *dfsdm,
 				  DFSDM_CR1_RSYNC(fl->sync_mode));
 }
 
-int stm32_dfsdm_channel_parse_of(struct stm32_dfsdm *dfsdm,
+static int stm32_dfsdm_channel_parse_of(struct stm32_dfsdm *dfsdm,
 					struct iio_dev *indio_dev,
 					struct iio_chan_spec *ch)
 {