Remove confusing log message

As noted in issue #382, logging when a parameter does not have
a mask is unnecessary and may confuse users.  Therefore, it is
removed.

distiller/scheduler.py

@@ -245,7 +245,6 @@ class ParameterMasker(object):
     def apply_mask(self, parameter):
         """Apply a mask on the weights tensor (parameter)."""
         if self.mask is None:
-            msglogger.debug('No mask for parameter {0}'.format(self.param_name))
             return
         if self.use_double_copies:
             self.unmasked_copy = parameter.clone().detach()