fix: completion wait after, maybe can't clean the flag.

    OXape reports: http://www.rt-thread.org/phpBB3/topic3939.html
          driver/ringbuffer: when data length is bigger than space length
          for rb, the read_index in rb is not update.
    When length > space, update the read_index, the bug can be fix, and
          works fine.

2. Fix data transfer size calculate error issue;

[USB]fix rt_usbd_set_config() BUG which set the USB device to configuration state before enumerating the device.

2.adjust some viable and micro name
3.some other small fix

This reverts commit 5aeedc4f, reversing
changes made to 3d80e414.

This merge breaks every uart driver in all BSPs. @bright-pan , is there
any way to get this done without breaking existing code?

Add hardware flow support.
Use new struct serial_ringbuffer.