Active Display: Disable proximity sensor when screen goes on in ActiveDisplay/PocketMode

Active Display (in Pocket Mode) currently only switches off the proximity sensor in some cases.
If the user switches on the screen itself, the sensor is left running. This change
stops the sensor as soon as the screen goes on. Active Display already started the sensor each
time the screen goes off.

PS2: In the mode that turns the screen off again when the device is pocketed,
the sensor stays on until you leave ActiveDisplay.