Systimer test : compilation error with MBED_TICKLESS

Issue occurs when "MBED_TICKLESS" is added in mbed_app.json,
not when "MBED_TICKLESS" is added in targets.json

Author: jeromecoutant

TESTS/mbedmicro-rtos-mbed/systimer/main.cpp

@@ -13,7 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-#if !MBED_TICKLESS
+#ifndef MBED_TICKLESS
 #error [NOT_SUPPORTED] Tickless mode not supported for this target.
 #endif