[mlir][math] Polynomial Approx tests are broken

[Mogball]

Many of math dialect operations now have folders, but that means the tests in math-polynomial-approx.mlir are broken because they are not testing the numerical approximation of the ops but instead the folders.

The test needs to be rewritten to pass in the constants via function arguments so that the ops don't fold.

[llvmbot]

@llvm/issue-subscribers-mlir

[jacquesguan]

Fixed in d67603a.

[Mogball]

Thanks!