Fix logic error in D79508. The old logic would make the first check in
`GPUFuncOp::verifyBody` always pass.
Add additional logic in `GPUFuncOp::verifyBody` to ensure the numbers got match
Since `workgroup_attributions` is added while parsing `gpu.func` op, it's not
possible to come up with a unit test which deliberately populate incorrect
number of `workgroup_attributions` therefore no unit test is added in this