I'm guessing that it is his real name for the following reasons:
1. It was his name back when he was the lowly guitar player for Nine Inch Nails............
2. He is the brother of Robert Patrick, who is an actor who has starred in many films + the Sopranos but is still best known for his role as the T1000 terminator in the Terminator sequel, T2: Judgement Day.
Since they both share the same last name........it's doubtfull that either are fabricated stage names.