The arguments in BufferedTx are flipped

[lasseslips]

The baud rate and the frequency are supposed to be flipped as seen here:

class BufferedTx(frequency: Int, baudRate: Int) extends Module {
  val io = IO(new Bundle {
    val txd = Output(UInt(1.W))
    val channel = Flipped(new UartIO())
  })
  val tx = Module(new Tx(frequency, baudRate))
  val buf = Module(new Buffer())

  buf.io.in <> io.channel
  tx.io.channel <> buf.io.out
  io.txd <> tx.io.txd
}