[ARM] Fast-Isel was incorrectly selecting <2 x double> adds.

With neon enabled, we reach SelectBinaryFPOp and are able to get registers for a <2 x double> add.

However, we shouldn't actually attempt arithmetic on it as ARMIselLowering says "v2f64 is legal so that QR subregs can be extracted as f64 elements, but neither Neon nor VFP support any arithmetic operations on it."

This commit disables SelectBinaryFPOp for any vector types.  There's already a FIXME to try handle neon.  Doing so would require fixing this conditional which isn't safe for vectors 'VT == MVT::f64 || VT == MVT::i64'

llvm-svn: 236609