[RISCV] Use non-VP select in gather->strided load combine. NFCish (llvm#157070)

Similar to llvm#157068, remove our reliance on trivial VP intrinsics by
using a regular select instruction and letting RISCVVLOptimizer take
care of VL.

Author: lukel97

llvm/lib/Target/RISCV/RISCVISelLowering.cpp

@@ -20546,9 +20546,9 @@ SDValue RISCVTargetLowering::PerformDAGCombine(SDNode *N,
             VT, DL, MGN->getChain(), BasePtr,
             DAG.getSignedConstant(StepNumerator, DL, XLenVT), MGN->getMask(),
             EVL, MGN->getMemOperand());
-        SDValue VPSelect = DAG.getNode(ISD::VP_SELECT, DL, VT, MGN->getMask(),
-                                       StridedLoad, MGN->getPassThru(), EVL);
-        return DAG.getMergeValues({VPSelect, SDValue(StridedLoad.getNode(), 1)},
+        SDValue Select = DAG.getSelect(DL, VT, MGN->getMask(), StridedLoad,
+                                       MGN->getPassThru());
+        return DAG.getMergeValues({Select, SDValue(StridedLoad.getNode(), 1)},
                                   DL);
       }
     }