Get rid of some unnecessary commented out code (issue #6849)

There is a lot of false positives (see [attached logs](http://code.google.com/p/sympy/issues/detail?id=3750#c1)), so I don't think that we should automate such cleanup.

fixes #6849
> since it is clear today what those defaults should be

I don't think there should be any "defaults".  If match was succesful - we have valid k and l.