When removing a port and immediately add it back we will receive this warning: unable to send packet on real device for Ethernet4: No such device or address

[tomer-israel]

Bug description

when we remove a port and add it back immediately - lldpd is keep failing and cannot recover.
warning message keeps appearing:

[WARN/lldp] unable to send packet on real device for Ethernet4: No such device or address

the socket keeps failing when trying to send lldp packets.
this problem is related to the timer that aggregate events from netlink and only 1 second after the last event the ports will be updated:
event.c lines 738-756

if we will remove the port and immediately add the port back the deletion of the port will not be executed.
when we remove a port and add it back we have a new ifindex and the socket that we used for this port is no longer relevant since we have a new ifindex for this port.
in these cases we need to recreate the socket with the new ifindex.

Steps to reproduce the problem

remove a port and immediately add the port back, for example:

Expected outcome

no warning on log and lldp packets will be sent properly

Current outcome

Additional information