[LegalizeVectorOps] Remove some of the simpler Expand methods. Pass Results...

[LegalizeVectorOps] Remove some of the simpler Expand methods. Pass Results vector to a couple. NFCI

Some of the simplest handlers just call TLI and if that fails,
they fall back to unrolling. For those just inline the TLI call
and share the unrolling call with the default case of Expand.

For ExpandFSUB and ExpandBITREVERSE so that its obvious they
don't return results sometimes and want to defer to LegalizeDAG.