bonding: elminate bad refcount code

The "expected_refcount" stuff in bonding sysfs module is a mistake.
Sysfs does proper refcounting, and it is okay to remove a bond device
that has some user process holding the file open.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>