[X86] Update TTI to report that v1iX/v1fX types aren't legal for masked gather/scatter/load/store.

The type legalizer will try to scalarize these operations if it sees them, but there is no handling for scalarizing them. This leads to a fatal error. With this change they will now be scalarized by the mem intrinsic scalarizing pass before SelectionDAG.

llvm-svn: 318380