bonding lacp: deleting virtual interface which was enslaved may cause crash

bonding lacp: deleting virtual interface which was enslaved may cause crash

Virtual interfaces may be part of the bonding like physical interfaces. The
difference is virtual interfaces may disappear dynamically. As an example,
the following CLI sequence may crash the debug image

create vhost-user socket /tmp/sock1
create bond mode lacp
bond add BondEthernet0 VirtualEthernet0/0/0
delete vhost-user VirtualEhernet0/0/0

Notice the virtual interface is deleted without first doing bond delete.
The proper order is to first remove the slave interface from the bond prior
to deleting the virtual interface as shown below. But we should handle it
anyway.

create vhost-user socket /tmp/sock1
create bond mode lacp
bond add BondEthernet0 VirtualEthernet0/0/0
bond del VirtualEthernet0/0/0   <-----
delete vhost-user VirtualEhernet0/0/0

The fix is to register for VNET_SW_INTERFACE_ADD_DEL_FUNCTION and remove
the slave interface from the bond if the to-be-deleted interface is part of
the bond. We check the interface that it is actually up before we send
the lacp pdu. Up means both hw and sw admin up.

Type: fix

Signed-off-by: Steven Luong <sluong@cisco.com>
Change-Id: If4d2da074338b16aab0df54e00d719e55c45221a