[AArch64] Simplify the Neon Scalar3Same patterns for floating-point reciprocal
step, floating-point reciprocal square root step, floating-point absolute
difference, and integer/floating-point compare instructions.  Also, move the
scalar general arithmetic operation patterns closer to similar code.  No
functional change intended.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@197250 91177308-0d34-0410-b5e6-96231b3b80d8