[mlir] Remove redudant default cases

These provide no value and trigger -Wcovered-switch-default.

Author: jpienaar

mlir/tools/mlir-tblgen/SPIRVUtilsGen.cpp

@@ -323,7 +323,6 @@ static void emitAvailabilityQueryForIntEnum(const Record &enumDef,
                     enumerant.getSymbol(), avail.getMergeInstanceType(),
                     avail.getMergeInstance());
     }
-    os << "  default: break;\n";
     os << "  }\n"
        << "  return llvm::None;\n"
        << "}\n";
@@ -368,7 +367,6 @@ static void emitAvailabilityQueryForBitEnum(const Record &enumDef,
                     enumerant.getSymbol(), avail.getMergeInstanceType(),
                     avail.getMergeInstance());
     }
-    os << "  default: break;\n";
     os << "  }\n"
        << "  return llvm::None;\n"
        << "}\n";
@@ -934,8 +932,6 @@ static void emitDeserializationDispatch(const Operator &op, const Record *def,
 /// of the operation.
 static void finalizeDispatchDeserializationFn(StringRef opcode,
                                               raw_ostream &os) {
-  os << "  default:\n";
-  os << "    ;\n";
   os << "  }\n";
   StringRef opcodeVar("opcodeString");
   os << formatv("  auto {0} = spirv::stringifyOpcode({1});\n", opcodeVar,