[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/MachineTraceMetrics.cpp b/llvm/lib/CodeGen/MachineTraceMetrics.cpp
index d81c6f8..1de0672 100644
--- a/llvm/lib/CodeGen/MachineTraceMetrics.cpp
+++ b/llvm/lib/CodeGen/MachineTraceMetrics.cpp
@@ -70,7 +70,7 @@
   TRI = ST.getRegisterInfo();
   MRI = &MF->getRegInfo();
   Loops = &getAnalysis<MachineLoopInfo>();
-  SchedModel.init(ST.getSchedModel(), &ST, TII);
+  SchedModel.init(&ST);
   BlockInfo.resize(MF->getNumBlockIDs());
   ProcResourceCycles.resize(MF->getNumBlockIDs() *
                             SchedModel.getNumProcResourceKinds());