[WebAssembly] Renumber SIMD bitwise instructions

Summary: Changed to match https://github.com/WebAssembly/simd/pull/54.

Reviewers: aheejin

Subscribers: dschuff, sbc100, jgravelle-google, sunfish, llvm-commits

Differential Revision: https://reviews.llvm.org/D54561

llvm-svn: 346931