Revert "Avoid peerUpdate logic in swarm mode"

This reverts commit b65a4ee10e2d34ba41d7d3447fd42c21a26b1ebb.

Signed-off-by: Flavio Crisciani <flavio.crisciani@docker.com>

libnetwork/drivers/overlay/peerdb.go

@@ -207,12 +207,6 @@ func (d *driver) peerDbDelete(nid, eid string, peerIP net.IP, peerIPMask net.IPM
 }
 
 func (d *driver) peerDbUpdateSandbox(nid string) {
-	// The following logic is useful only in non swarm mode
-	// In swarm mode instead the programmig will come directly from networkDB
-	if !d.isSerfAlive() {
-		return
-	}
-
 	d.peerDb.Lock()
 	pMap, ok := d.peerDb.mp[nid]
 	if !ok {