MT6572 UART进meta设定

http://blog.csdn.net/sergeycao/article/details/8953848

MT6572 USB pin可以与uart1和uart2做share pin.   MT6572这边会增加一个宏(CFG_USB_UART_SWITCH_PORT)来决定,默认是uart2.
 
#define CFG_UART_LOG                (UART2)
#define CFG_UART_META               (UART1)
#define CFG_USB_UART_SWITCH_PORT    (UART2)
 
 72的config =>透过USB PIN配置连接为Uart2，可以修改为Uart1，连接Meta 和抓log.
  #define CFG_UART_LOG               (UART2)
#define CFG_UART_META             (UART1)