I want to add a field in drupal commerce products by default like commerce_price?
The hook you're trying to use is unrelated to Field API fields, unfortunately. You should look at the commerce_product.module and commerce_product_ui.module files to see how I did it in core for the default price field. Either on module enable or when a new product type is created via the UI, I call the commerce_product_type_configure() function that in turn adds the default price field to the product type. You'll want a similar function that you can invoke when a module is enabled or on hook_commerce_product_type_insert() to add your custom fields.