Fix that when I go to display size in the settings, the largest size shows the smallest icons.

Root cause:
Preview didn't instantly be updated when scrolling the Display size.

Solution:
Get the value from preferences when scrolling, and from the display size data value when initializing.

Fix: 248748575
Test: manual test
Change-Id: I441766e0fd97ec1ac287d5bd4191693b2490c552