Many USB serial ports do not support a 5 bits per byte configuration however when
configuring a serial port under DOS it is fairly common practice to simply set the
serial ports LCR register to 0x80 to set the DLAB bit before setting the LCR to the
actually desired value. This patch is a hack to work around the problem with these
adapters at the cost of disabling the 9600 baud 5.N,1 configuration.