[SVE] Add SVE2 patterns for unpredicated multiply instructions

Summary:
Add patterns for SVE2 unpredicated multiply instructions:
- mul, smulh, umulh, pmul, sqdmulh, sqrdmulh

Reviewers: sdesmalen, huntergr, efriedma, c-rhodes, kmclaughlin, rengolin

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

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D72799