[Conversion][FixedPointToInteger] Fix issue with `updateCallOp`

[zzzDavid]

Description

updateCallOp should update the result types of a func.call operation if any of the result type is a fixed point type memref or scalar.

This PR updates the type update judgement logic, from implementing the function's own to using the shared utility function convertFixedMemRefOrScalarToInt.

Test added

After this PR, the FixedToInteger pass should be able to pass functions with scalar return types, such as:

func.func @callee(%arg0: f32, %arg1: f32) -> f32 attributes {itypes = "__", otypes = "_"} {
    %0 = arith.addf %arg0, %arg1 : f32
    %alloc = memref.alloc() {name = "c"} : memref<1xf32>
    affine.store %0, %alloc[0] {to = "c"} : memref<1xf32>
    %1 = affine.load %alloc[0] {from = "c"} : memref<1xf32>
    %2 = affine.load %alloc[0] {from = "c"} : memref<1xf32>
    return %2 : f32
  }

  func.func @test_scalar_result_func_calls(%arg0: memref<10xf32>, %arg1: memref<10xf32>) -> memref<10xf32> attributes {itypes = "__", otypes = "_"} {
    %c0_i32 = arith.constant 0 : i32
    %0 = arith.sitofp %c0_i32 : i32 to f32
    %alloc = memref.alloc() {name = "C"} : memref<10xf32>
    linalg.fill ins(%0 : f32) outs(%alloc : memref<10xf32>)
    affine.for %arg2 = 0 to 10 {
      %1 = affine.load %arg0[%arg2] {from = "A"} : memref<10xf32>
      %2 = affine.load %arg1[%arg2] {from = "B"} : memref<10xf32>
      %3 = func.call @callee(%1, %2) : (f32, f32) -> f32
      affine.store %3, %alloc[%arg2] {to = "C"} : memref<10xf32>
    } {loop_name = "i", op_name = "S_i_0"}
    return %alloc : memref<10xf32>
  }

This test is added to test/Transforms/datatype/fixedpoint.mlir