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.h b/compiler/optimizing/code_generator.h
index c7623fe..74ad8e9 100644
--- a/compiler/optimizing/code_generator.h
+++ b/compiler/optimizing/code_generator.h
@@ -168,8 +168,8 @@
   void AllocateRegistersLocally(HInstruction* instruction) const;
 
   // Backend specific implementation for allocating a register.
-  virtual ManagedRegister AllocateFreeRegister(Primitive::Type type,
-                                               bool* blocked_registers) const = 0;
+  virtual Location AllocateFreeRegister(Primitive::Type type,
+                                        bool* blocked_registers) const = 0;
 
   // Raw implementation of allocating a register: loops over blocked_registers to find
   // the first available register.