bonding: process lacp when bond is admin down

bonding: process lacp when bond is admin down

Ticket: VPP-1821
Type: fix
Fixes: 6dfd3785e4

When a bond interface is administratively down but the slaves are
up, process inbound LACP packets received over the slaves. This
was the old behavior with bond interfaces in LACP mode and was
altered unintentionally by another change. Restore the old behavior.

Change-Id: I61b0b700211dea4859b6ee447ab83b33197d9d11
Signed-off-by: Matthew Smith <mgsmith@netgate.com>
(cherry picked from commit 854eb6e3ff87ace211a45a8053424d8432bd5755)