Refine current-task check in mo_task_suspend()

The previous implementation compared `kcb->task_current` with the task’s
list node in the global task list. A list node is only a linkage
element, not a stable identifier for a task, so this comparison is not
appropriate.

This patch updates the check to compare the task's data structure (TCB),
which properly represents the task identity.

Author: vicLin8712

kernel/task.c

@@ -883,7 +883,7 @@ int32_t mo_task_suspend(uint16_t id)
     }
 
     task->state = TASK_SUSPENDED;
-    bool is_current = (kcb->task_current == node);
+    bool is_current = (kcb->task_current->data == task);
 
     CRITICAL_LEAVE();