AArch64: Add missing scalar pair intrinsics.
E.g. "float32_t vaddv_f32(float32x2_t a)" to be matched into "faddp s0, v1.2s".


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@196199 91177308-0d34-0410-b5e6-96231b3b80d8