[BRIDGE]: generate kobject remove event

The earlier round of kobject/sysfs changes to bridge caused
it not to generate a uevent on removal. Don't think any application
cares (not sure about Xen) but since it generates add uevent
it should generate remove as well.

Signed-off-by: Stephen Hemminger <shemmigner@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>