USB: ftdi_sio: Fix locking for change_speed() function

The change_speed() function should be serialized against multiple calls.
Use the cfg_lock mutex to do this.

Signed-off-by: Alessio Igor Bogani <abogani@texware.it>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 file changed