BugLink: http://bugs.launchpad.net/bugs/1562310

Similar to other helpers, caller can use this to find out if device is
team master.
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit c981e421)
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>