net: bridge: add notifications for the bridge dev on vlan change

Currently the bridge device doesn't generate any notifications upon vlan
modifications on itself because it doesn't use the generic bridge
notifications.
With the recent changes we know if anything was modified in the vlan config
thus we can generate a notification when necessary for the bridge device
so add support to br_ifinfo_notify() similar to how other combined
functions are done - if port is present it takes precedence, otherwise
notify about the bridge. I've explicitly marked the locations where the
notification should be always for the port by setting bridge to NULL.
I've also taken the liberty to rearrange each modified function's local
variables in reverse xmas tree as well.

Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>