[bugfix]components:libc:cplusplus: Repair the comment code.

utest:tc_atomic.cpp
      Modify the comments of the functions utest_tc_init, utest_tc_cleanup, testcase and UTEST_TC_EXPORT in tc_atomic.cpp.
    On the premise of conforming to RT-Thread coding standards,
    maintain consistency with the comment style of the tc_thread.cpp file.
signed-off-by: Liu Chengtao<[email protected]>

Author: lct1001

components/libc/cplusplus/utest/tc_atomic.cpp

@@ -158,7 +158,7 @@ static void test_atomic_basic_int64(void)
 
     val.fetch_and(14);
     uassert_int_equal(val.load(), 10);
-    
+
     val.fetch_or(11); /* 1010 */
     uassert_int_equal(val.load(), 11);
 
@@ -239,13 +239,19 @@ static void test_compare_exchange_weak(void)
     }
     uassert_int_equal(val.load(), 2);
 }
-/* Test case initialization function. */
+/**
+ * @brief Test case initialization function.
+ * @return RT_EOK on success.
+ */
 static rt_err_t utest_tc_init(void)
 {
     return RT_EOK;
 }
 
-/* Test case cleanup function.*/
+/**
+ * @brief Test case cleanup function.
+ * @return RT_EOK on success.
+ */
 static rt_err_t utest_tc_cleanup(void)
 {
     return RT_EOK;