Fix #1009, add missing clock retcode tests

Note that the success case for OS_SetLocalTime is tested,
but is marked as a MIR test case because it requires
elevated permission, it is expected to fail when running
as a normal user on Linux.

src/os/inc/osapi-clock.h

@@ -83,6 +83,7 @@ enum
  * @param[out]  time_struct An OS_time_t that will be set to the current time
  *
  * @return Get local time status, see @ref OSReturnCodes
+ * @retval #OS_SUCCESS @copybrief OS_SUCCESS
  * @retval #OS_INVALID_POINTER if time_struct is null
  */
 int32 OS_GetLocalTime(OS_time_t *time_struct);
@@ -98,6 +99,7 @@ int32 OS_GetLocalTime(OS_time_t *time_struct);
  * @param[in]  time_struct An OS_time_t containing the current time
  *
  * @return Set local time status, see @ref OSReturnCodes
+ * @retval #OS_SUCCESS @copybrief OS_SUCCESS
  * @retval #OS_INVALID_POINTER if time_struct is null
  */
 int32 OS_SetLocalTime(const OS_time_t *time_struct);

src/unit-tests/oscore-test/ut_oscore_misc_test.c

@@ -295,7 +295,7 @@ void UT_os_setlocaltime_test()
     /*-----------------------------------------------------*/
     /* #1 Null-pointer-arg */
 
-    UT_RETVAL(OS_GetLocalTime(NULL), OS_INVALID_POINTER);
+    UT_RETVAL(OS_SetLocalTime(NULL), OS_INVALID_POINTER);
 
     /*-----------------------------------------------------*/
     /* #3 Nominal */