[MachineBlockPlacement] trivial fix in comments, NFC
[MachineBlockPlacement] trivial fix in comments, NFC

- Topologocal is abbreviated as "topo" in comments, but "top" is used in only one comment. Modify it for consistency.
- Capitalize "succ" and "pred" for consistency in one figure.
- Other trivial fixes.



git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@305552 91177308-0d34-0410-b5e6-96231b3b80d8

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