Don't look for the TargetFrameLowering in the implementation

The same oddity was apparently copy-pasted between multiple targets.

llvm-svn: 364349
diff --git a/llvm/lib/Target/AMDGPU/SIFrameLowering.cpp b/llvm/lib/Target/AMDGPU/SIFrameLowering.cpp
index 8ded85f..6226b78 100644
--- a/llvm/lib/Target/AMDGPU/SIFrameLowering.cpp
+++ b/llvm/lib/Target/AMDGPU/SIFrameLowering.cpp
@@ -826,8 +826,7 @@
   bool IsDestroy = Opc == TII->getCallFrameDestroyOpcode();
   uint64_t CalleePopAmount = IsDestroy ? I->getOperand(1).getImm() : 0;
 
-  const TargetFrameLowering *TFI = MF.getSubtarget().getFrameLowering();
-  if (!TFI->hasReservedCallFrame(MF)) {
+  if (!hasReservedCallFrame(MF)) {
     unsigned Align = getStackAlignment();
 
     Amount = alignTo(Amount, Align);