Use lambda on all kernel prim ops

This makes executorch_prim::et_copy_index.tensor and
executorch_prim::et_view.default also use a lamba function like the
rest. This fixes a problem where the functions pointers didn't get
proper values for this two ops.

Signed-off-by: Zingo Andersen <zingo.andersen@arm.com>
Change-Id: Icc2623c5fe730483ddb21f041fe52de03f63a953