tests: drivers: pwm: pwm_api: Missing sleep statement

If a board runs this test at a high frequency,
they will see a noticable skip of a test due to
a missing k_sleep function that allows the pwm
time to display the requested pwm signal.

Signed-off-by: Emilio Benavente <emilio.benavente@nxp.com>

tests/drivers/pwm/pwm_api/src/test_pwm.c

@@ -159,4 +159,5 @@ ZTEST_USER(pwm_basic, test_pwm_cycle)
 	/* Period : Pulse (64000 : 0), unit (cycle). Voltage : 0V */
 	zassert_true(test_task(DEFAULT_PWM_PORT, DEFAULT_PERIOD_CYCLE,
 				0, UNIT_CYCLES) == TC_PASS, NULL);
+	k_sleep(K_MSEC(1000));
 }