tests: drivers: adc: adc_dma: increase sampling interval for MCUX ADC16

Increase hardware sampling interval to 30ms for MCUX ADC16. The ADC
callback in the repeated_samplings test takes roughly 27ms to execute,
so a sampling frequency of this interval still allows the ADC test to
verify the ADC is being sampled at a given interval, while avoiding the
pitfalls that result from a kernel timer shorter than the duration the
ADC callback takes to run.

Fixes zephyrproject-rtos#58467

Signed-off-by: Daniel DeGrasse <daniel.degrasse@nxp.com>

tests/drivers/adc/adc_dma/src/test_adc.c

@@ -23,7 +23,7 @@
 #define ADC_ACQUISITION_TIME ADC_ACQ_TIME_DEFAULT
 #define ADC_1ST_CHANNEL_ID 26
 #define COUNTER_NODE_NAME pit0
-#define HW_TRIGGER_INTERVAL (2U)
+#define HW_TRIGGER_INTERVAL (30000U)
 #define SAMPLE_INTERVAL_US HW_TRIGGER_INTERVAL
 
 #elif defined(CONFIG_BOARD_FRDM_K82F)
@@ -35,7 +35,7 @@
 #define ADC_ACQUISITION_TIME ADC_ACQ_TIME_DEFAULT
 #define ADC_1ST_CHANNEL_ID 26
 #define COUNTER_NODE_NAME pit0
-#define HW_TRIGGER_INTERVAL (2U)
+#define HW_TRIGGER_INTERVAL (30000U)
 #define SAMPLE_INTERVAL_US HW_TRIGGER_INTERVAL
 
 #elif defined(CONFIG_BOARD_NUCLEO_H743ZI)