Fixes AMDMfmaEncodingAttr::toLinearLayout to support smaller/refined sizes. Before, too many register bases were being supplied so that ExtractSliceOpToLLVM was calculating the wrong number of elements in packLLElements. Now the right number of register basis vectors are emplated in the newly created linear layout.
Add support for refining element-wise ops, including ConvertLayout, also ExpandDims and Broadcast.

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