Do not redispatch/inject motionevent to private virtual display

The virtaul display with private flag can't be access by other process.
To prevent AceesibilityService redispatches/injects motionevents on it,
We don't add it to valid displayList.

Bug: 138637403
Test: AccessibilityInputFilterTest
Test: AccessibilityGestureDectorTest
Change-Id: I7b60e4eee87b0812d3c882d0e45bbf2016190e6a