Well, if all of your apps and OS run fine, do not worry about it.
Now, the bad news. This is a bga socketed processor, which means it cannot be replaced - unless you have a very good extended warranty with DELL. If you do, then DELL could replace the motherboard. If not, you are out of luck.
Well I have a good extended warranty. But dell has its own supportassist app, on which the processor tests are not failing. How do I convince them about the problem with the processor, since they do not accept intel tests?
I cannot help you with that. Dell is solely responsible for support of your laptop. The IPDT failing may be a fluke, since Dell's test passed and you are not experiencing other problems.
Whatever the case, this is between you and Dell.