Teach UiModeMgr about high-end and low-end desk docks.

Should fix dock mode on Stingray, since its docks advertise
themselves as EXTRA_DOCK_STATE_LE_DESK and
EXTRA_DOCK_STATE_HE_DESK but not EXTRA_DOCK_STATE_DESK.

Bug: 5569662
Change-Id: I93197665c0df8dea06ca8fadae97ec267c751c85