Remove commented-out import in binary_code.py (#1263)

Trivial code health cleanup: remove the unnecessary commented-out import
of `_binary_polynomial` in
`src/openfermion/ops/operators/binary_code.py.

Author: mhucka

src/openfermion/ops/operators/binary_code.py

@@ -19,8 +19,6 @@
 
 from openfermion.ops.operators import BinaryPolynomial
 
-# import openfermion.ops.operators._binary_polynomial as bp
-
 
 def shift_decoder(decoder, shift_constant):
     """Shifts the indices of a decoder by a constant.