Fix initialization with CH340 UARTs

Initialization is messed up with older Linux kernels and that
results in 9600 baud being used unconditionally. Setting the baud
rate separately seems to work around this successfully.

stcgal/protocols.py

@@ -732,8 +732,11 @@ class StcBaseProtocol:
         Set up serial port, send sync sequence and get part info.
         """
 
-        self.ser = serial.Serial(port=self.port, baudrate=self.baud_handshake,
+        self.ser = serial.Serial(port=self.port,
                                  parity=self.PARITY)
+        # set baudrate separately to workaround a bug with the CH340 driver
+        # in older Linux kernels
+        self.ser.baudrate = self.baud_handshake
 
         # fast timeout values to deal with detection errors
         self.ser.timeout = 0.5