[X86] Merge 8-bit instructions into instregex with 16/32/64 instructions in the scheduler models as much as possible. NFCI

This reduces the total number of generated scheduler classes from 5404 to 5316.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@327815 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed