samples: drivers: adc: Allow coverage calculation.

Sample must end to dump coverage data.

Signed-off-by: Bartlomiej Buczek <bartlomiej.buczek@nordicsemi.no>

samples/drivers/adc/adc_dt/src/main.c

@@ -54,7 +54,11 @@ int main(void)
 		}
 	}
 
+#ifndef CONFIG_COVERAGE
 	while (1) {
+#else
+	for (int k = 0; k < 10; k++) {
+#endif
 		printk("ADC reading[%u]:\n", count++);
 		for (size_t i = 0U; i < ARRAY_SIZE(adc_channels); i++) {
 			int32_t val_mv;

samples/drivers/adc/adc_sequence/src/main.c

@@ -56,7 +56,11 @@ int main(void)
 		}
 	}
 
+#ifndef CONFIG_COVERAGE
 	while (1) {
+#else
+	for (int k = 0; k < 10; k++) {
+#endif
 		printf("ADC sequence reading [%u]:\n", count++);
 		k_msleep(1000);