Fix for LLDP related netlink error messages

Fix for LLDP related netlink error messages

Ticket: CM-27243
Reviewed By: CCR-9608
Testing Done: Unit tseting, PTM Smoke

Issue: Error messages "netlink: 8 bytes leftover after parsing attributes
in process `lldpd'"

Root cause: Root Cause: The length of the netlink message was not being set
properly for non-bridge family type messages. Same length was being used for
both type of messages even though bridge family type message has extra
attribute. This causes 8 extra bytes being left over in the non-bridge
family type netlink messages.

Fix: Calculating and setting the length separately for bridge and non-bridge
family type messages.
(cherry picked from commit aac76966539bf932d5923b165762db370990bf94)