[X86][Btver2] Add CVTSD2SI/CVTSS2SI scheduler costs

Account for the "+i" integer pipe transfer cost (1cy use of JALU0 for GPR PRF write)

This also adds missing vcvttss2si tests 

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@328505 91177308-0d34-0410-b5e6-96231b3b80d8
6 files changed