[llvm] MTM: fix style after cursory reading (NFC) (PR #100404)

[Michael Maitland via llvm-commits]

================
@@ -852,14 +846,14 @@ computeInstrDepths(const MachineBasicBlock *MBB) {
   // implies Head->HasValidInstrDepths, so we only need to start from the first
   // block in the trace that needs to be recomputed.
   SmallVector<const MachineBasicBlock*, 8> Stack;
-  do {
+  while (MBB) {
----------------
michaelmaitland wrote:

Is this one NFC though?

https://github.com/llvm/llvm-project/pull/100404