Fix SVE2.1 quadword gather load/scatter store intrinsics

[momchil-velikov]

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[andrewcarlotti]

Is there a reason to exclude 8-bit types from the index intrinsics, aside from it being equivalent to the offset intrinsics in those cases?

[momchil-velikov]

Is there a reason to exclude 8-bit types from the index intrinsics, aside from it being equivalent to the offset intrinsics in those cases?

No, that's the only reason.

[vhscampos]

LGTM. Thanks