[InstCombine] Improve bitreverse optimization

This patch utilizes the helper function implemented in D149699 and thus folds the following cases:

```
bitreverse(logic_op(x, bitreverse(y))) -> logic_op(bitreverse(x), y)
bitreverse(logic_op(bitreverse(x), y)) -> logic_op(x, bitreverse(y))
bitreverse(logic_op(bitreverse(x), bitreverse(y))) -> logic_op(x, y) in multiuse case
```

Reviewed By: goldstein.w.n, RKSimon

Differential Revision: https://reviews.llvm.org/D151246