Bump up MAX_SUBTARGET_FEATURES

Bump up MAX_SUBTARGET_FEATURES

Summary:
Currently, ARMGenSubtargetInfo (from ARM.td) is reaching the limit of 96:
  enum : uint64_t {
       ...
       XScale = 95
  };

We need to bump the maximum value up to accommodate future changes and/or customized subtarget definitions.

Reviewers: apazos, t.p.northover

Subscribers: llvm-commits, aemerson

Differential Revision: http://reviews.llvm.org/D15514

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@255616 91177308-0d34-0410-b5e6-96231b3b80d8