[llvm] [TableGen] Use PrintFatalError in ParseTreePattern for proper error handling of llvm-tblgen (PR #161417)

[Prerona Chaudhuri via llvm-commits]

pchaudhuri-nv wrote:

Also, I have fixed only few of the asserts. If you want, I will change all the asserts to PrintFatalError. Kindly let me know.

Thank you

https://github.com/llvm/llvm-project/pull/161417