Tweak LPC1768 upload py script

Marlin/src/HAL/HAL_LPC1768/upload_extra_script.py

@@ -16,10 +16,11 @@ current_OS = platform.system()
 Import("env")
 
 def print_error(e):
-    print('\nUnable to find destination disk (' + e + ')\n' \
+	print('\nUnable to find destination disk (%s)\n' \
 		  'Please select it in platformio.ini using the upload_port keyword ' \
 		  '(https://docs.platformio.org/en/latest/projectconf/section_env_upload.html) ' \
-          'or copy the firmware (.pio/build/' + env.get('PIOENV') + '/firmware.bin) manually to the appropriate disk\n')
+		  'or copy the firmware (.pio/build/%s/firmware.bin) manually to the appropriate disk\n' \
+		  %(e, env.get('PIOENV')))
 
 try:
 	if current_OS == 'Windows':