[TargetSchedule] shrink interface for init(); NFCI

The TargetSchedModel is always initialized using the TargetSubtargetInfo's 
MCSchedModel and TargetInstrInfo, so we don't need to extract those and 
pass 3 parameters to init().

Differential Revision: https://reviews.llvm.org/D44789

llvm-svn: 329540
diff --git a/llvm/lib/CodeGen/MachineCombiner.cpp b/llvm/lib/CodeGen/MachineCombiner.cpp
index efb463f..498b4cb 100644
--- a/llvm/lib/CodeGen/MachineCombiner.cpp
+++ b/llvm/lib/CodeGen/MachineCombiner.cpp
@@ -633,7 +633,7 @@
   TII = STI->getInstrInfo();
   TRI = STI->getRegisterInfo();
   SchedModel = STI->getSchedModel();
-  TSchedModel.init(SchedModel, STI, TII);
+  TSchedModel.init(STI);
   MRI = &MF.getRegInfo();
   MLI = &getAnalysis<MachineLoopInfo>();
   Traces = &getAnalysis<MachineTraceMetrics>();