veth: drop iface peer check during create_and_realize()

When fetching the parent device, if the system is slow, NetworkManager
can hit a race condition where the property is still NULL. In that case,
NetworkManager should create the veth link.

Checking that the peer device exists, it is type NM_DEVICE_TYPE_VETH and
it have a parent device is enough to know that we can skip the link
creation.

https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/merge_requests/1399

https://bugzilla.redhat.com/show_bug.cgi?id=2129829

Fixes: 4655b7c308 ('veth: fix veth activation on booting')

src/core/devices/nm-device-veth.c

@@ -101,8 +101,8 @@ create_and_realize(NMDevice              *device,
     peer        = nm_setting_veth_get_peer(s_veth);
     peer_device = nm_manager_get_device(NM_MANAGER_GET, peer, NM_DEVICE_TYPE_VETH);
     if (peer_device) {
-        /* The veth device and its peer already exist. No need to create it again. */
-        if (nm_streq0(nm_device_get_iface(nm_device_parent_get_device(peer_device)), iface))
+        if (nm_device_parent_get_device(peer_device))
+            /* The veth device and its peer already exist. No need to create it again. */
             return TRUE;
     }