[mlir] Remove unused variables. No functionality change.

The compiler will start warning on them with an upcoming mlir change.

PiperOrigin-RevId: 289096631
diff --git a/iree/compiler/Dialect/VM/IR/VMOps.cpp b/iree/compiler/Dialect/VM/IR/VMOps.cpp
index ad1f3ed..5cf0978 100644
--- a/iree/compiler/Dialect/VM/IR/VMOps.cpp
+++ b/iree/compiler/Dialect/VM/IR/VMOps.cpp
@@ -678,7 +678,6 @@
   assert(isBuildableWith(value, value.getType()));
   Builder builder(value.getContext());
   int32_t dims = 1;
-  Attribute newValue;
   if (value.isa<UnitAttr>()) {
     return builder.getI32IntegerAttr(1);
   } else if (auto v = value.dyn_cast<BoolAttr>()) {
@@ -1093,7 +1092,6 @@
 static ParseResult parseCallVariadicOp(OpAsmParser &parser,
                                        OperationState *result) {
   FlatSymbolRefAttr calleeAttr;
-  FunctionType calleeType;
   auto calleeLoc = parser.getNameLoc();
   if (failed(parser.parseAttribute(calleeAttr, "callee", result->attributes)) ||
       failed(parser.parseLParen())) {