Fix network examples (#2256)

* examples/networking: remove the deprecated pyroute2 functions

link_create() and link_remove() are deprecated since pyroute2 0.5.2.
Replace them with the equivalent link() commands.

Signed-off-by: Gary Lin <glin@suse.com>
diff --git a/examples/networking/simulation.py b/examples/networking/simulation.py
index 2c6a0f3..5395d5d 100644
--- a/examples/networking/simulation.py
+++ b/examples/networking/simulation.py
@@ -49,7 +49,7 @@
         else:
             # delete the potentially leaf-over veth interfaces
             ipr = IPRoute()
-            for i in ipr.link_lookup(ifname='%sa' % ifc_base_name): ipr.link_remove(i)
+            for i in ipr.link_lookup(ifname='%sa' % ifc_base_name): ipr.link("del", index=i)
             ipr.close()
             try:
                 out_ifc = self.ipdb.create(ifname="%sa" % ifc_base_name, kind="veth",