[AArch64]Fix the assertion failure caused by "v1i1 SETCC" DAG node.
As v1i1 is illegal, the type legalizer tries to scalarize such node. But if the type operands of SETCC is legal, the scalarization algorithm will cause an assertion failure.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@201381 91177308-0d34-0410-b5e6-96231b3b80d8