ethernet: prevent provisioning failure loop

Adds check to restart() to prevent an endless provisioning failure loop
that could occur when link disappears while an interface is
provisioning (triggering a subsequent provisioning failure, restart,
and so on).

Test: atest EthernetManagerTest
Bug: 265255745
Change-Id: I83decad4eae5bb1070204997bb0acd35ba4cc9f4
1 file changed