Remove code copied from GenRegisterInfo.inc.

There's no apparent reason this code was copied from generated source
into a .cpp. It sets a bad example for those working on other targets
and trying to understand the register info API.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@175849 91177308-0d34-0410-b5e6-96231b3b80d8