PPC: Fix "[fullcodegen] Add support for %_GetSuperConstructor."

Use appropriate load instruction for 32-bit mode.

R=bmeurer@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com
BUG=v8:3330
LOG=n

Review URL: https://codereview.chromium.org/1532673002

Cr-Commit-Position: refs/heads/master@{#32917}

src/full-codegen/ppc/full-codegen-ppc.cc

@@ -3746,8 +3746,8 @@ void FullCodeGenerator::EmitGetSuperConstructor(CallRuntime* expr) {
   DCHECK_EQ(1, args->length());
   VisitForAccumulatorValue(args->at(0));
   __ AssertFunction(r3);
-  __ ld(r3, FieldMemOperand(r3, HeapObject::kMapOffset));
-  __ ld(r3, FieldMemOperand(r3, Map::kPrototypeOffset));
+  __ LoadP(r3, FieldMemOperand(r3, HeapObject::kMapOffset));
+  __ LoadP(r3, FieldMemOperand(r3, Map::kPrototypeOffset));
   context()->Plug(r3);
 }