tests-mbed_drivers-lp_timeout: Rework "Zero delay" test case

Execute test case 100 times in loop since one run is not enough to catch possible failure.

Author: mprse

TESTS/mbed_drivers/timeout/timeout_tests.h

@@ -196,13 +196,14 @@ void test_multiple(void)
 template<typename T>
 void test_no_wait(void)
 {
-    Semaphore sem(0, 1);
-    T timeout;
-    timeout.attach_callback(mbed::callback(sem_callback, &sem), 0ULL);
-
-    bool acquired = sem.try_acquire();
-    TEST_ASSERT_TRUE(acquired);
-    timeout.detach();
+    for (int i = 0; i < 100; i++) {
+        Semaphore sem(0, 1);
+        T timeout;
+        timeout.attach_callback(mbed::callback(sem_callback, &sem), 0ULL);
+        int32_t sem_slots = sem.wait(0);
+        TEST_ASSERT_EQUAL(1, sem_slots);
+        timeout.detach();
+    }
 }
 
 /** Template for tests: accuracy of timeout delay