[MPS] Fix base shape size for view ops in case of multiple slices (#85934)
Fixes https://github.com/pytorch/pytorch/issues/84364, https://github.com/pytorch/pytorch/issues/85592
Fixes bug for view ops where the base shape would be incorectly determined.
E.g for the following tensor `torch.tensor([0.5, 0.5], device="mps")[1][None]`, we could consider the base shape of the parent tensor as 1, while the actual base shape is 2.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/85934
Approved by: https://github.com/kulinseth
