Fix chamtool: upgrade command gives exception

(cherry picked from commit 592b851)

Software/Chameleon/Device.py

@@ -251,4 +251,7 @@ class Device:
             return self.getSetCmd(self.COMMAND_THRESHOLD, value)
 
     def cmdUpgrade(self):
-        return self.execCmd(self.COMMAND_UPGRADE)
+        # Execute command
+        cmdLine = self.COMMAND_UPGRADE + self.LINE_ENDING
+        self.serial.write(cmdLine.encode('ascii'))
+        return 0

Software/chamtool.py

@@ -143,8 +143,10 @@ def cmdThreshold(chameleon, arg):
             return "Setting threshold failed: {}".format(arg, result['statusText'])
 
 def cmdUpgrade(chameleon, arg):
-    result = chameleon.cmdUpgrade()
-    return ""
+    if(chameleon.cmdUpgrade() == 0):
+        print ("Device changed into Upgrade Mode")
+    exit(0)
+
 # Custom class for argparse
 class CmdListAction(argparse.Action):
     def __init__(self, option_strings, dest, default=False, required=False,