[AArch64] Add support for NEON scalar absolute value instruction.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192842 91177308-0d34-0410-b5e6-96231b3b80d8
[AArch64] Add support for NEON scalar negate instruction.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192843 91177308-0d34-0410-b5e6-96231b3b80d8