Remove ptei->value check from ipfw_link_table_values():

even if there was non-zero number of restarts, we would unref/clear
all value references and start ipfw_link_table_values() once again
with (mostly) cleared "tei" buffer.

Additionally, ptei->ptv stores only to-be-added values, not existing ones.
This is a forgotten piece of previous value refconting implementation,

and now it is simply incorrect.