PPC: [turbofan] Fix loading of JSFunction from activation in case of adapter frame.

Port ebc51674

Original commit message:

R=mbrandy@us.ibm.com

BUG=

Review URL: https://codereview.chromium.org/1016003005

Cr-Commit-Position: refs/heads/master@{#27486}

src/compiler/ppc/code-generator-ppc.cc

@@ -1222,7 +1222,7 @@ void CodeGenerator::AssemblePrologue() {
     if (FLAG_code_comments) __ RecordComment("-- OSR entrypoint --");
     osr_pc_offset_ = __ pc_offset();
     // TODO(titzer): cannot address target function == local #-1
-    __ lwa(r4, MemOperand(fp, JavaScriptFrameConstants::kFunctionOffset));
+    __ LoadP(r4, MemOperand(fp, JavaScriptFrameConstants::kFunctionOffset));
     DCHECK(stack_slots >= frame()->GetOsrStackSlotCount());
     stack_slots -= frame()->GetOsrStackSlotCount();
   }