net: drop if expression that is always true

Both is_netdev and !is_netdev paths already check that
net_client_init_func[opts->kind] is non-NULL so there is no need for the
if statement.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-id: 1432743412-15943-5-git-send-email-stefanha@redhat.com