l3cfg: schedule an update after every commit type register/unregister
After every commit type register we increase the reference count of the NML3Cfg object if a new handle have been created. When unregistering we decrease the reference count and we do the same when adding/removing a new NML3ConfigData object. At these points we need to schedule a commit that will also trigger ECMP commit.
During ECMP commit we track/untrack all the ECMP routes so we make sure that during NML3Cfg finalize the ECMP route tracking (ecmp_track_ifindex_lst_head) list is empty.