Move setDisplayViewport to InputReader.

InputReader is responsible to associate device and display so it makes
sense to allow it set display viewport for pointer controller.

Bug: 146385350
Test: Cursor can be associated with external freeform displays as
expected.

Change-Id: I00d664dd180f1e693b1900582feea8f7ff02f93c
Merged-In: I00d664dd180f1e693b1900582feea8f7ff02f93c