bridge: trigger RTM_NEWLINK when interface is modified by bridge ioctl

Currently, there is a difference in netlink events received when an
interface is modified through bridge ioctl() or through netlink. This
patch generates additional events when an interface is added to or
removed from a bridge via ioctl().

When adding then removing an interface from a bridge with netlink, we
get:

5: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue master bridge0 state UNKNOWN group default
    link/ether 9e:da:60:ee:cf:c8 brd ff:ff:ff:ff:ff:ff
5: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 master bridge0 state UNKNOWN
    link/ether 9e:da:60:ee:cf:c8
5: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 master bridge0 state UNKNOWN
    link/ether 9e:da:60:ee:cf:c8
5: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 master bridge0 state UNKNOWN
    link/ether 9e:da:60:ee:cf:c8
5: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 master bridge0 state UNKNOWN
    link/ether 9e:da:60:ee:cf:c8
5: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue master bridge0 state UNKNOWN group default
    link/ether 9e:da:60:ee:cf:c8 brd ff:ff:ff:ff:ff:ff

5: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue master bridge0 state UNKNOWN group default
    link/ether 9e:da:60:ee:cf:c8 brd ff:ff:ff:ff:ff:ff
5: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 master bridge0 state UNKNOWN
    link/ether 9e:da:60:ee:cf:c8
Deleted 5: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 master bridge0 state UNKNOWN
    link/ether 9e:da:60:ee:cf:c8
5: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default
    link/ether 9e:da:60:ee:cf:c8 brd ff:ff:ff:ff:ff:ff

When using ioctl():

5: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue master bridge0 state UNKNOWN group default
    link/ether 9e:da:60:ee:cf:c8 brd ff:ff:ff:ff:ff:ff
5: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 master bridge0 state UNKNOWN
    link/ether 9e:da:60:ee:cf:c8
5: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 master bridge0 state UNKNOWN
    link/ether 9e:da:60:ee:cf:c8
5: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 master bridge0 state UNKNOWN
    link/ether 9e:da:60:ee:cf:c8
5: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue master bridge0 state UNKNOWN group default
    link/ether 9e:da:60:ee:cf:c8 brd ff:ff:ff:ff:ff:ff

5: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue master bridge0 state UNKNOWN group default
    link/ether 9e:da:60:ee:cf:c8 brd ff:ff:ff:ff:ff:ff
5: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 master bridge0 state UNKNOWN
    link/ether 9e:da:60:ee:cf:c8
Deleted 5: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 master bridge0 state UNKNOWN
    link/ether 9e:da:60:ee:cf:c8
5: dummy1: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default
    link/ether 9e:da:60:ee:cf:c8 brd ff:ff:ff:ff:ff:ff

Without this patch, the last netlink notification is not sent.

Signed-off-by: Vincent Bernat <vincent@bernat.im>
Reviewed-by: Stephen Hemminger <stephen@networkplumber.org>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>