The standby controller would potentially fail to boot while
attempting to PXE-boot when configured with a management LAG.
This commit determines the interface with the lowest slave MAC
address in an active_standby LAG configuration and assigns it
as the primary interface.
Story: 2002865
Task: 22814
Change-Id: I73f03cb9cb2fd632a1e64b4e7744e3be067318a4
Signed-off-by: Jack Ding <jack.ding@windriver.com>
3347cd311a