Fixed an issue with rt_timer_start being broken and destroying the timer list

Author: Guozhanxin

src/timer.c

@@ -331,7 +331,6 @@ rt_err_t rt_timer_start(rt_timer_t timer)
     _rt_timer_remove(timer);
     /* change status of timer */
     timer->parent.flag &= ~RT_TIMER_FLAG_ACTIVATED;
-    rt_hw_interrupt_enable(level);
 
     RT_OBJECT_HOOK_CALL(rt_object_take_hook, (&(timer->parent)));
 
@@ -342,9 +341,6 @@ rt_err_t rt_timer_start(rt_timer_t timer)
     RT_ASSERT(timer->init_tick < RT_TICK_MAX / 2);
     timer->timeout_tick = rt_tick_get() + timer->init_tick;
 
-    /* disable interrupt */
-    level = rt_hw_interrupt_disable();
-
 #ifdef RT_USING_TIMER_SOFT
     if (timer->parent.flag & RT_TIMER_FLAG_SOFT_TIMER)
     {