Revert "Set priority among various display devices"

* This reverts commit 52b4fdbdbd4b935c48164542cdd1f4a1292cb08a.

* Since DisplayDevices are not created for non-wfd virtual
displays(CTS/SR/SSD) anymore, we can remove these checks.

Change-Id: I9249a70c6d6f6b42f268e6ec8a28c0a86b954c4e
3 files changed