[SVE] Pass Scalable argument to VectorType::get in Bitcode Reader

Summary:
* Pass the Scalability test to VectorType::get in order to be
able to deserialize bitcode that contains scalable vector operations

Change-Id: I37fe5b1c0c237a9153130deefdc1a6d595c7f12e

Reviewers: efriedma, pcc, sdesmalen, apazos, huihuiz, chrisj

Reviewed By: sdesmalen

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

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D72792