[MLIR] Don't sort operand of commutative ops when comparing two ops as there is a correctness issue

This feature was introduced in `D123492`.

Doing equivalence on pointers to sort operands of commutative operations is incorrect when checking equivalence of ops in separate regions (where the lhs and rhs operands are marked as equivalent but are not the same value).

It was also discussed in `D123492` and `D129480` that the correct solution would be to stable sort the operands in canonicalization (based on some numbering in the region maybe), but until that lands, reverting this change will unblock us and other users.

An example of a pass that might not work properly because of this is `DuplicateFunctionEliminationPass`.

Reviewed By: mehdi_amini, jpienaar

Differential Revision: https://reviews.llvm.org/D154699