[DebugInfo][NFC] Remove `FuncArgumentDbgValueKind::Addr` from SelectionDAG

This removes the unused `FuncArgumentDbgValueKind::Addr` value originally added
by e24f5348. The intent was to signal the
original intrinsic that marked a function argument, but the `Addr` part was
never used.

Part of `dbg.addr` removal
Discussed in https://discourse.llvm.org/t/what-is-the-status-of-dbg-addr/62898

Differential Revision: https://reviews.llvm.org/D144794