[SVE][IR] Small TypeSize improvements left out of initial commit

The commit for D53137 left out the last round of improvements
requested by reviewers. Adding those in now.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@375013 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed