doc change: "Work Policy Controller" to "device policy controller".

Bug: 24062075
Change-Id: I74287445d2268d0cc3752f09b8e326d210d84444
Staged:
https://x20web.corp.google.com/~katarina/Android%206.0%20Changes%20_%20Android%20Developers.html
https://x20web.corp.google.com/~katarina/Android%206.0%20APIs%20_%20Android%20Developers.html
2 files changed