RT-Thread/ART — pull request #1 by rogerz (2012-07-07 08:30:48+00:00)
Title: Fix usart init error which will cause assert failure

Uninitialized struct member may cause assert failure in `NVIC_Init()`

assert_param(IS_NVIC_PREEMPTION_PRIORITY(NVIC_InitStruct->NVIC_IRQChannelPreemptionPriority));