[CodeGen] Fix warnings in LowerToPredicatedOp

[david-arm]

Summary

When creating a new vector type based on another vector type we
should pass in the element count instead of the number of elements
and scalable flag separately.

I encountered this warning whilst compiling this test:

CodeGen/AArch64/sve-intrinsics-int-compares.ll

[kmclaughlin]

LGTM!

llvm/lib/Target/AArch64/AArch64ISelLowering.cpp

SDValue AArch64TargetLowering::LowerToPredicatedOp(SDValue Op,
                                         unsigned NewOp) const {
   EVT VT = Op.getValueType();
   SDLoc DL(Op);
 
   assert(Op.getOperand(0).getValueType().isScalableVector() &&
          Op.getOperand(1).getValueType().isScalableVector() &&
          "Only scalable vectors are supported");
 
-  auto PredTy = VT.getVectorVT(*DAG.getContext(), MVT::i1,
-                               VT.getVectorNumElements(), true);
+  auto PredTy =
+      VT.getVectorVT(*DAG.getContext(), MVT::i1, VT.getVectorElementCount());
   SDValue Mask = getPTrue(DAG, DL, PredTy, AArch64SVEPredPattern::all);
 
   SmallVector<SDValue, 4> Operands = {Mask};
   Operands.append(Op->op_begin(), Op->op_end());
   return DAG.getNode(NewOp, DL, VT, Operands);
 }
 
 static bool resolveBuildVector(BuildVectorSDNode *BVN, APInt &CnstBits,