only use proximity checks on wakeup keys

The power button should always wake the screen regardless of the
proximity; only check proximity when the wake up key code is WAKEUP.

Ticket: CYNGNOS-2579

Change-Id: I686ad22d513a3d939be3a0a5c3b752339b2383d3
Signed-off-by: Roman Birg <roman@cyngn.com>