power: fix dock power applet disappear

caused by CL 699

Change-Id: I79e142f8bf70169ebb299524d321d804afd77c8f
tower: https://tower.im/projects/1c0cd0c59ef941298c6e6b2ba6833b91/todos/a6afb1ffe4214c4f9328ddc05890ed77/