[PowerPC]fix XRAY failures in https://lab.llvm.org/buildbot/#/builders/145/builds/726

Regression caused by 4321300.

Author: Chen Zheng

llvm/lib/Target/PowerPC/PPCAsmPrinter.cpp

@@ -1854,7 +1854,7 @@ void PPCLinuxAsmPrinter::emitInstruction(const MachineInstr *MI) {
       IsConditional = false;
     } else {
       EmitToStreamer(*OutStreamer, RetInst);
-      break;
+      return;
     }
 
     MCSymbol *FallthroughLabel;
@@ -1919,7 +1919,7 @@ void PPCLinuxAsmPrinter::emitInstruction(const MachineInstr *MI) {
     if (IsConditional)
       OutStreamer->emitLabel(FallthroughLabel);
     recordSled(BeginOfSled, *MI, SledKind::FUNCTION_EXIT, 2);
-    break;
+    return;
   }
   case TargetOpcode::PATCHABLE_FUNCTION_EXIT:
     llvm_unreachable("PATCHABLE_FUNCTION_EXIT should never be emitted");