datapath: backport: ovs/vxlan: fix rtnl notifications on iface deletion

datapath: backport: ovs/vxlan: fix rtnl notifications on iface deletion

At this point OVS tunneling is insync with upstream net
branch (commit 9a0fee2b552b1).

upstream commit:
    commit cf5da330bbdd0c06b05c525a3d1d58ccd82c87a6
    Author: Nicolas Dichtel <nicolas.dichtel@6wind.com>

    ovs/vxlan: fix rtnl notifications on iface deletion

    The function vxlan_dev_create() (only used by ovs) never calls
    rtnl_configure_link(). The consequence is that dev->rtnl_link_stat 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.

    Note that the function vxlan_dev_create() is moved after the rtnl stuff so
    that vxlan_dellink() can be called in this function.

    Fixes: dcc38c033b32 ("openvswitch: Re-add CONFIG_OPENVSWITCH_VXLAN")
    CC: Thomas Graf <tgraf@suug.ch>
    CC: Pravin B Shelar <pshelar@ovn.org>
    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>