Views module core patching inside a sub-site
Modules that are placed inside sites/all/modules directory are accessible to all sites setup inside sites directory. Thats why it is showing you the error.

So basically you are trying to apply a patch for pqr-child site only. So you can do :


If it is a general patch, you can apply it to sites/all/modules/views directory. So there is no need of adding views directory for pqr-child site.
If it is a hack, then my suggestion is not to hack the module, instead you can write a custom module to fulfil your requirements. 
But if it still necessary to hack the module, you need to copy the sites/all/modules/views to all the sites/subsites/modules directory and delete it from sites/all/modules.