net-sysfs: make sure objects belong to container's owner

net-sysfs: make sure objects belong to container's owner

BugLink: https://launchpad.net/bugs/1784501
When creating various objects in /sys/class/net/... make sure that they
belong to container's owner instead of global root (if they belong to a
container/namespace).

Co-Developed-by: Tyler Hicks <tyhicks@canonical.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit b0e37c0d8a6abed0cd1b611314a7ebf50b0a8ed4)
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Acked-by: Kleber Souza <kleber.souza@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>