ldpd: fix bug in pseudowire control-word negotiation
Bingen discovered a bug in the pseudowire control-word negotiation that
might happen when the "control-word exclude" command is used. Under some
very specific conditions, ldpd might ignore a PWID label mapping when
it shouldn't.
This patch removes a wrong optimization that was preventing ldpd to call
l2vpn_pw_reset() every time we change the configuration of a pseudowire.