Remove unused pmKey function

Found by Clang 3.4.

Change-Id: Ie4e9fc535ee44caae561aacdc245c64ea5b30b46
Reviewed-by: Robin Burchell <robin+qt@viroteck.net>
Merge remote-tracking branch 'origin/stable' into dev

Change-Id: I1acc7b8d54e8db1a3bec01c31c755032d24e8e64