[ARM64-BE] Correctly deal with single element HFAs in varargs.

Just because the first "if" didn't fire, doesn't mean we can not have
an HFA in the "else" clause.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@208216 91177308-0d34-0410-b5e6-96231b3b80d8
Re-satisfy the bots. Due to a de-sync between my clang and LLVM trees, I didn't notice that the generated BE alignment register is now unnamed and is not called '%align_be'.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@208217 91177308-0d34-0410-b5e6-96231b3b80d8