vxlan: add changelink support
This patch adds changelink rtnl op support for vxlan netdevs.
code changes involve:
- refactor vxlan_newlink into vxlan_nl2conf to be
used by vxlan_newlink and vxlan_changelink
- vxlan_nl2conf and vxlan_dev_configure take a
changelink argument to isolate changelink checks
and updates.
- Allow changing only a few attributes:
- return -EOPNOTSUPP for attributes that cannot
be changed for now. Incremental patches can
make the non-supported one available in the future
if needed.
Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>