tests: drivers: counter: Relax timing requirement

In short_relative_capable test it is possible that short alarm
setting is repeated few times and it is possible that alarm
does not expire shortely after setting. Increase the delay after
expiration is checked.

Signed-off-by: Krzysztof Chruscinski <krzysztof.chruscinski@nordicsemi.no>

tests/drivers/counter/counter_basic_api/src/test_counter.c

@@ -804,7 +804,7 @@ static void test_short_relative_alarm_instance(const struct device *dev)
 				dev->name, err);
 
 		/* wait to ensure that tick+1 timeout will expire. */
-		k_busy_wait(3*tick_us);
+		k_busy_wait(10 * tick_us);
 
 		cnt = IS_ENABLED(CONFIG_ZERO_LATENCY_IRQS) ?
 			alarm_cnt : k_sem_count_get(&alarm_cnt_sem);