[LegalizeTypes] Remove the call to SplitVecRes_UnaryOp from SplitVecRes_StrictFPOp. NFCI

It doesn't seem to do anything that SplitVecRes_StrictFPOp can't
do. SplitVecRes_StrictFPOp already handles nodes with a variable
number of arguments and a mix of scalar and vector arguments.