[X86] Split off PHMINPOSUW to their own schedule class

This also fixes Jaguar's schedule which was treating it as the WriteVecIMul default. 

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@330756 91177308-0d34-0410-b5e6-96231b3b80d8
13 files changed