Stop converting from Location to ManagedRegister.

Now the source of truth is the Location object that knows
which register (core, pair, fpu) it needs to refer to.

Change-Id: I62401343d7479ecfb24b5ed161ec7829cda5a0b1
diff --git a/compiler/optimizing/code_generator_x86.h b/compiler/optimizing/code_generator_x86.h
index 3e2ca90..c520164 100644
--- a/compiler/optimizing/code_generator_x86.h
+++ b/compiler/optimizing/code_generator_x86.h
@@ -167,7 +167,7 @@
 
   virtual size_t GetNumberOfRegisters() const OVERRIDE;
   virtual void SetupBlockedRegisters(bool* blocked_registers) const OVERRIDE;
-  virtual ManagedRegister AllocateFreeRegister(
+  virtual Location AllocateFreeRegister(
       Primitive::Type type, bool* blocked_registers) const OVERRIDE;
 
   virtual Location GetStackLocation(HLoadLocal* load) const OVERRIDE;