[SVE] Eliminate calls to default-false VectorType::get() from IR

Reviewers: efriedma, kmclaughlin, sdesmalen, dexonsmith, dblaikie

Reviewed By: efriedma

Subscribers: tschuett, hiraditya, rkruppe, psnobl, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D80261