iio: adc: stm32: add tim15 trigger

Add TIM15_TRGO trigger that is now supported on STM32H7.
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/stm32-adc.c

@@ -531,6 +531,7 @@ static struct stm32_adc_trig_info stm32h7_adc_trigs[] = {
 	{ TIM2_TRGO, STM32_EXT11 },
 	{ TIM4_TRGO, STM32_EXT12 },
 	{ TIM6_TRGO, STM32_EXT13 },
+	{ TIM15_TRGO, STM32_EXT14 },
 	{ TIM3_CH4, STM32_EXT15 },
 	{ LPTIM1_OUT, STM32_EXT18 },
 	{ LPTIM2_OUT, STM32_EXT19 },