[Hexagon] Adding xtype doubleword comparisons.  Removing unused multiclass.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223701 91177308-0d34-0410-b5e6-96231b3b80d8
[Hexagon] Adding xtype doubleword add, sub, and, or, xor and patterns.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223702 91177308-0d34-0410-b5e6-96231b3b80d8