tests/drivers/adc/adc_api/ fails on sam_e70_xplained

[nniranjhana]

The test in tests/drivers/adc/adc_api/ fails with Assertion Failure on sam_e70_xplained.

The test started failing after this commit: 4e551aa

Arch: ARM
Platform: sam_e70_xplained

Error console log:

 ***** delaying boot 1000ms (per build configuration) *****
 ***** Booting Zephyr OS 1.13.0-rc1 (delayed boot 1000ms) *****
 Running test suite adc_basic_test
 ===================================================================
 starting test - test_adc_sample_one_channel
 [dev/adc_sam_afec] [ERR] start_read: Spaced intervals not supported
E#1      @jfsotc06/same70-29k  console output:
     Assertion failed at ../zephyr/tests/drivers/adc/adc_api/src/test_adc.c:219: test_task_one_channel: (ret not equal to 0)
 adc_read() failed with code -22
 FAIL - test_adc_sample_one_channel
 ===================================================================
 starting test - test_adc_sample_two_channels
 SKIP - test_adc_sample_two_channels
 ===================================================================
 starting test - test_adc_asynchronous_call

[nashif]

fixed by #9815