net/core: Allow certain receives on inactive slave.

Allow a packet_type that specifies the exact device to receive
even on an inactive bonding slave devices.  This is important for some
L2 protocols such as LLDP and FCoE.  This can eventually be used
for the bonding special cases as well.

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>