[mlir][tosa] Fix dynamic shape inference in conv2d

[mlir][tosa] Fix dynamic shape inference in conv2d

The comment in the code correctly states the equation for the shape inference as follows:

```
H = ((IH+pad_top+pad_bottom-(dilation_y*(KH-1)+1))/stride_y)+1
```

However the final operation is generated as `-` instead of `+`. I believe `+`
is indeed correct. For example if we have an image with dimension 6 and kernel
of dimension 3 (assuming padding is 0 and stride and dilation are both 1) we
are expecting 4 elements in the output (computed for image elements `(0, 1, 2)
x kernel`, `(1, 2, 3) x kernel`, `(2, 3, 4) x kernel` and `(3, 4, 5) x kernel`.
However currently only 2 elements are produced in the output.

Reviewed By: NatashaKnk

Differential Revision: https://reviews.llvm.org/D133208