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/locations.cc b/compiler/optimizing/locations.cc
index 7b09241..1637484 100644
--- a/compiler/optimizing/locations.cc
+++ b/compiler/optimizing/locations.cc
@@ -55,7 +55,7 @@
       : Location::RequiresRegister();
 }
 
-Location Location::ByteRegisterOrConstant(ManagedRegister reg, HInstruction* instruction) {
+Location Location::ByteRegisterOrConstant(int reg, HInstruction* instruction) {
   return instruction->IsConstant()
       ? Location::ConstantLocation(instruction->AsConstant())
       : Location::RegisterLocation(reg);