[SVE] Remove calls to VectorType::getNumElements from Bitcode

Reviewers: efriedma, evgeny777, tejohnson, david-arm, kmclaughlin

Reviewed By: david-arm

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

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D82209