sensors: Fix ALS and PS lag on back-compat layer

These 2 sensors only report values on change,
instead of continuously generating samples at 'setDelay'
intervals like most others. If only these 2 (or any one of
them is enabled), we can't wait for the usual 64 samples
to be taken before reporting them to the framework, since
that'll make them visibly laggy.

This patch causes any sample from these sensors to trigger
an immediate report to the client.

Change-Id: Id5932376858c30323bff07ac4b38856dc200d074