PPC: [turbofan] Add TruncateFloat32ToUint32 operator to Turbofan.

Port 2166bd8c

R=joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com
BUG=

Review URL: https://codereview.chromium.org/1677213002

Cr-Commit-Position: refs/heads/master@{#33830}

src/compiler/ppc/instruction-selector-ppc.cc

@@ -1021,12 +1021,12 @@ void InstructionSelector::VisitTruncateFloat64ToInt32(Node* node) {
 
 
 void InstructionSelector::VisitTruncateFloat32ToInt32(Node* node) {
-  return VisitRR(this, kPPC_DoubleToInt32, node);
+  VisitRR(this, kPPC_DoubleToInt32, node);
 }
 
 
 void InstructionSelector::VisitTruncateFloat32ToUint32(Node* node) {
-  UNIMPLEMENTED();
+  VisitRR(this, kPPC_DoubleToUint32, node);
 }