bonding: fire NETDEV_RELEASE event only on 0 slaves

bonding: fire NETDEV_RELEASE event only on 0 slaves

[ Upstream commit 80028ea1c0afc24d4ddeb8dd2a9992fff03616ca ]

Currently, if we set up netconsole over bonding and release a slave,
netconsole will stop logging on the whole bonding device. Change the
behavior to stop the netconsole only when the last slave is released.

Signed-off-by: Veaceslav Falico <vfalico@redhat.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>