overlay: writeback: Do not create writeback instance on dumpsys

Do not create a writeback instance during dumpsys.
Instead use the dumpsys to return empty if no instance exists.
This fixes the issue where
a) Unnecessary instance is created.
b) Dumpsys has garbage, if a valid instance didn't exist

b/8316155 - Implement HWComposer 1.3 w/ virtual display support
Change-Id: Ic8ea5ddd8d05203234da7c7dfccd2c2b497e62f7
3 files changed
tree: b9db8ca3243f306d82dbda4d431be9a849db1e87
  1. Android.mk
  2. msm8960/
  3. msm8974/
  4. msm8x26/