[X86] Generalize X86FixupLEAs to work with TargetSchedModel
[X86] Generalize X86FixupLEAs to work with TargetSchedModel

Similar to rL329834, don't rely on itinerary scheduler model to determine latencies for LEA thresholds, use the generic TargetSchedModel::computeInstrLatency call.

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@330030 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,llvm-mirror/llvm,apple/swift-llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,apple/swift-llvm