GPU Codegen bug: bad cast of input scalar

Dear DaCe team,

We encountered a bug in the codegen ([SDFG linked](https://github.com/user-attachments/files/28771136/bad_cast_on_scalar.sdfgz.zip) and repro' below).

The quirk is that a tasklet takes a `np.float32` scalar but is given a `np.float64` - this triggers a malformed cast inside the kernel on the callsite of a nested function, e.g.

```c++
void nested_sdfg_0_0_3(const double& scalar, float* __restrict__ out_field, int __i, int __j);

__global__ void __launch_bounds__(32) horizontal_loop_139965476328208_0_0_5(float * __restrict__ stencil_out, const double stencil_scalar) {
#code removed
nested_sdfg_0_0_3(*(float *)(&stencil_scalar), &stencil_out[0], __i, __j);
#--------------------------------^ bad idea
}
```

Rep:
```python
import dace

sdfg = dace.SDFG.from_file("./bad_cast_on_scalar.sdfgz.zip")
sdfg.compile()
```