Revert "Content description for padlock icon depending on state"

This reverts commit 1518196a94ed006b2b45e5dc527a23721ec1147a.

It turned out that just "Unlock" is a better label there, as
announcing the state might be confusing.

Bug: 17255298
Change-Id: I13f3b3db68f3f96afcd4db33baf07e7e213aa12c