MIPS: Fix of r16681

Use v0 for return value.

BUG=
R=gergely@homejinni.com

Review URL: https://codereview.chromium.org/23437032

Patch from Balazs Kilvady <kilvadyb@homejinni.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16694 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/mips/builtins-mips.cc

@@ -337,7 +337,7 @@ void Builtins::Generate_InRecompileQueue(MacroAssembler* masm) {
 
   CallRuntimePassFunction(masm, Runtime::kTryInstallRecompiledCode);
   // Tail call to returned code.
-  __ Addu(at, a2, Operand(Code::kHeaderSize - kHeapObjectTag));
+  __ Addu(at, v0, Operand(Code::kHeaderSize - kHeapObjectTag));
   __ Jump(at);
 
   __ bind(&ok);