Print display ids of Virtual Displays too

This impact the output of `dumpsys SurfaceFlinger --display-id`.

Note: this will output the ids of the same displays than
`dumpsys SurfaceFlinger --displays`. Similar to that command, phyical
displays will be enumerated first.

Fix: 403588742
Flag: EXEMPT (small change in dumpsys)
Test: build and run with an overlay
Change-Id: I176b0894c3dd4fc2ecd30809ed117b87464f8d85