netdevice: provide common routine for macvlan and vlan operstate management

Provide common routine for the transition of operational state for a leaf
device during a root device transition.

Signed-off-by: Patrick Mullaney <pmullaney@novell.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>