datapath: backport: ovs/gre,geneve: fix error path when creating an iface

datapath: backport: ovs/gre,geneve: fix error path when creating an iface

Upstream commit:
    commit 106da663ff495e0aea3ac15b8317aa410754fcac
    Author: Nicolas Dichtel <nicolas.dichtel@6wind.com>

    ovs/gre,geneve: fix error path when creating an iface

    After ipgre_newlink()/geneve_configure() call, the netdev is registered.

    Fixes: 7e059158d57b ("vxlan, gre, geneve: Set a large MTU on ovs-created tunnel devices")
    CC: David Wragg <david@weave.works>
    Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Pravin B Shelar <pshelar@ovn.org>
Acked-by: Jesse Gross <jesse@kernel.org>