Print region argument only when argAttrs are present

Fixes: #132894

Author: hiraditya

mlir/test/Analysis/invalid-entry-block.mlir

@@ -0,0 +1,13 @@
+// Bug: https://github.com/llvm/llvm-project/issues/132894
+
+// RUN: not mlir-opt %s 2>&1 | FileCheck %s
+
+// CHECK: error: 'func.func' op entry block must have 1 arguments to match function signature
+
+module {
+  func.func @f(f32) {
+    %c0 = arith.constant 0 : index
+    return
+  }
+}
+