bgpd: fix more regressions in attr flag checks

Commit 05a4936b713b9882171d0f7fb20b8439df23939e fixed some of the
attributes involved, but not all. This commit should do it.

* bgp_attr.c
  * bgp_attr_originator_id()
  * bgp_attr_cluster_list()
  * bgp_mp_reach_parse()
  * bgp_mp_unreach_parse()
1 file changed