Make REDUCE_MOTION setting permanently readable.

This setting is dependent by wear material library and is used by 3p
apps. So we have to make it permanently readable to avoid breaking 3p
apps.

Flag: EXEMPT trivial change
Bug: 349362071
Fix: 349362071
Test: build success
Change-Id: Ief2abf30f479adacf5b04312a7422d2f9b7a5082