uart works in linux
uart works in linux

dev/tsunami_uart.cc:
    added code make it work with linux's uart code.

haowu4682/gem5,LingxiaoJIA/gem5,andrewfu0325/gem5-aladdin,haowu4682/gem5,haowu4682/gem5,LingxiaoJIA/gem5,andrewfu0325/gem5-aladdin,haowu4682/gem5,andrewfu0325/gem5-aladdin,haowu4682/gem5,LingxiaoJIA/gem5,haowu4682/gem5,LingxiaoJIA/gem5,LingxiaoJIA/gem5,andrewfu0325/gem5-aladdin,haowu4682/gem5,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,haowu4682/gem5,LingxiaoJIA/gem5,LingxiaoJIA/gem5,haowu4682/gem5