When the processed lldp data is used for setting the local_link_connection
switch_id, it will set it even if the Chassis ID is not a mac. Need to
only set it when the ChassisId is a mac address, as is done when using
non-processed lldp data. Ironic validates that switch_id is either a
mac address or OpenFlow datapath ID.
This fixes a regresssion introduced in Pike.
Change-Id: I566acb5b19852b541df7554870ab2666f7df9614
Closes-Bug: 1748022