[Hexagon] Adding compare with immediate instructions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222792 91177308-0d34-0410-b5e6-96231b3b80d8
Reverting 222792

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222793 91177308-0d34-0410-b5e6-96231b3b80d8
[Hexagon] Adding add64 and sub64 instructions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222795 91177308-0d34-0410-b5e6-96231b3b80d8