When posture changes, re-register prox listeners

Listeners that were skipped from registering
because the previous posture didn't support prox
need to be re-registered.

Test: atest PostureDependentProximitySensorTest
Test: enter AOD from the unfolded state and then
close the phone. From AOD in the folded state,
cover the prox sensor => observe that AOD display
turns off after 10+ seconds.
Fixes: 272691904

Change-Id: Ib8a72c2af01a546019ef4a611ca9877e20881346