[AMDGPU] Remove dead early-out in GCNHazardRecognizer

[critson]

Summary

Remove an early-out in wait state counting which can never be
taken.

[critson]

Remove extra line.

[foad]

LGTM.

Just to explain a bit more, I think that once we get to this check, one of the recursive calls on getWaitStatesSince must already have called IsExpired with the same WaitStates value, and that call can't have returned true otherwise getWaitStatesSince would have returned INTMAX and we'd have taken the continue on line 428. (This is assuming that the various IsExpiredFns are fairly sane in that they don't interpret their WaitStates argument differently depending on whether their MI argument is null or not.)

llvm/lib/Target/AMDGPU/GCNHazardRecognizer.cpp

for (MachineBasicBlock *Pred : MBB->predecessors()) {
 
     int W = getWaitStatesSince(IsHazard, Pred, Pred->instr_rbegin(),
                                WaitStates, IsExpired, Visited);
 
     if (W == std::numeric_limits<int>::max())
       continue;
 
     MinWaitStates = Found ? std::min(MinWaitStates, W) : W;
-    if (IsExpired(nullptr, MinWaitStates))
-      return MinWaitStates;
-
     Found = true;
   }
 
   if (Found)
     return MinWaitStates;
 
   return std::numeric_limits<int>::max();
 }