erl_interface,ic: Remove node_org_enc from erlang_{pid,port,ref}

in order to be backward compatible with user code that
accesses the members of erlang_pid and friend.

The documentation does not mention the content of these structs,
but we have example code that does. So the safe way it the revert
the node_org_enc field (added in R16A) and instead determine in
runtime which atom encoding to use depending on if the node atom
contains unicode (>255) characters or not.