[VirtRegMap] Simplify condition after #65729

Author: jayfoad

llvm/lib/CodeGen/VirtRegMap.cpp

@@ -275,7 +275,7 @@ bool VirtRegRewriter::runOnMachineFunction(MachineFunction &fn) {
   // Rewrite virtual registers.
   rewrite();
 
-  if (DebugVars && ClearVirtRegs) {
+  if (ClearVirtRegs) {
     // Write out new DBG_VALUE instructions.
 
     // We only do this if ClearVirtRegs is specified since this should be the