Keyguard - Fix clock in occluded state

The status area (clock, smartspace) was not being shown after exiting
an activity on the lockscreen. The y translation value was incorrect
for the branch it was taking. Add a new check for occlusion, and use
the correct transition when leaving this state.

Fixes: 184188027
Test: manual (use emergency call button)
Change-Id: I6fa34e55252ac8435031915a7e929711e7976fe2