net/core: Allow receive on active slaves.

If a packet_type specifies an active slave to bonding and not just any
interface, allow it to receive frames that came in on that interface.

Signed-off-by: Joe Eykholt <jre@nuovasystems.com>
Signed-off-by: Jay Vosburgh <fubar@us.ibm.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>