Make management interface name configurable.
Make management interface name configurable.

Summary:
Open network linux uses ma1 instead of eth0 for management interface.
Let's add a flag so that it will work.

Reviewed By: aeckert

Differential Revision: D2826068

fb-gh-sync-id: 8a447cf09e0ef9bff382973296296ca69570e6f2

peterlei/fboss,neuhausler/fboss,peterlei/fboss,peterlei/fboss,neuhausler/fboss,peterlei/fboss,neuhausler/fboss,neuhausler/fboss