networkd: don't filter on udev tags

This removed the requirement for devices to be tagged with
'systemd-networkd' before they will be visible to networkd.

Still, as by default we don't ship any .network files, network
devices will simply be tracked, but not touched, unless the
admin configures things explicitly.

src/network/networkd-manager.c

@@ -101,6 +101,8 @@ static int manager_process_link(Manager *m, struct udev_device *device) {
         if (streq_ptr(udev_device_get_action(device), "remove")) {
                 uint64_t ifindex;
 
+                log_debug("Link removed: %s", udev_device_get_sysname(device));
+
                 ifindex = udev_device_get_ifindex(device);
                 link = hashmap_get(m->links, &ifindex);
                 if (!link)
@@ -108,6 +110,8 @@ static int manager_process_link(Manager *m, struct udev_device *device) {
 
                 link_free(link);
         } else {
+                log_debug("New link: %s", udev_device_get_sysname(device));
+
                 r = link_add(m, device);
                 if (r < 0) {
                         log_error("Could not handle link %s: %s",
@@ -136,10 +140,6 @@ int manager_udev_enumerate_links(Manager *m) {
         if (r < 0)
                 goto finish;
 
-        r = udev_enumerate_add_match_tag(e, "systemd-networkd");
-        if (r < 0)
-                goto finish;
-
         r = udev_enumerate_scan_devices(e);
         if (r < 0)
                 goto finish;
@@ -197,12 +197,6 @@ int manager_udev_listen(Manager *m) {
                 return r;
         }
 
-        r = udev_monitor_filter_add_match_tag(m->udev_monitor, "systemd-networkd");
-        if (r < 0) {
-                log_error("Could not add udev monitor filter: %s", strerror(-r));
-                return r;
-        }
-
         r = udev_monitor_enable_receiving(m->udev_monitor);
         if (r < 0) {
                 log_error("Could not enable udev monitor");