ovs/geneve: fix rtnl notifications on iface deletion

ovs/geneve: fix rtnl notifications on iface deletion

The function geneve_dev_create_fb() (only used by ovs) never calls
rtnl_configure_link(). The consequence is that dev->rtnl_link_state is
never set to RTNL_LINK_INITIALIZED.
During the deletion phase, the function rollback_registered_many() sends
a RTM_DELLINK only if dev->rtnl_link_state is set to RTNL_LINK_INITIALIZED.

Fixes: e305ac6cf5a1 ("geneve: Add support to collect tunnel metadata.")
CC: Pravin B Shelar <[email protected]>
CC: Jesse Gross <[email protected]>
CC: Thomas Graf <[email protected]>
Signed-off-by: Nicolas Dichtel <[email protected]>
Signed-off-by: David S. Miller <[email protected]>