Ignore 'dynamic' addr flag on bridge configuration

When setting the bridge up, if that flag is present but not
ignored, the delete command will fail and may leave the
interface and the bridge in an inconsistent state.

Closes-Bug: #1274611
Related-Bug: #1077066
Change-Id: Iff65d61d724d0de5d8173ac37f7f748aa23e5d8b
Merge "Ignore 'dynamic' addr flag on bridge configuration"