Demo fix for readability-redundant-control-flow (WIP)

[Eugene.Zelenko]

By the word, I run this check over entire LLVM code base (but only X86 architecture) and there were only 8 detected occurrences. It make sense to fix them across entire code base and enable check on top level .clang-tidy.

mlir/lib/Dialect/OpenMP/IR/OpenMPDialect.cpp

 /// Printer for AtomicReadOp
 static void printAtomicReadOp(OpAsmPrinter &p, AtomicReadOp op) {
   p << " " << op.address() << " ";
   if (op.memory_order())
     p << "memory_order(" << op.memory_order().getValue() << ") ";
   if (op.hintAttr())
     printSynchronizationHint(p << " ", op, op.hintAttr());
   p << ": " << op.address().getType() << " -> " << op.getType();
-  return;
 }
 
 /// Verifier for AtomicReadOp
 static LogicalResult verifyAtomicReadOp(AtomicReadOp op) {
   if (op.memory_order()) {
     StringRef memOrder = op.memory_order().getValue();
     if (memOrder.equals("acq_rel") || memOrder.equals("release"))
       return op.emitError(

 /// Printer for AtomicWriteOp
 static void printAtomicWriteOp(OpAsmPrinter &p, AtomicWriteOp op) {
   p << " " << op.address() << ", " << op.value() << " ";
   if (op.memory_order())
     p << "memory_order(" << op.memory_order() << ") ";
   if (op.hintAttr())
     printSynchronizationHint(p, op, op.hintAttr());
   p << ": " << op.address().getType() << ", " << op.value().getType();
-  return;
 }
 
 /// Verifier for AtomicWriteOp
 static LogicalResult verifyAtomicWriteOp(AtomicWriteOp op) {
   if (op.memory_order()) {
     StringRef memoryOrder = op.memory_order().getValue();
     if (memoryOrder.equals("acq_rel") || memoryOrder.equals("acquire"))
       return op.emitError(