Revert "Update documentation for DISPLAY_DECORATION"

Revert "Add/plumb SurfaceControl.DISPLAY_DECORATION"

Revert "Add eLayerIsDisplayDecoration flag"

Revert submission 16511727-wm_DISPLAY_DECORATION

Reason for revert: b/211835607
Reverted Changes:
I1da3199ba:Allow changing composition from DISPLAY_DECORATION...
I1fae74b36:Update documentation for DISPLAY_DECORATION
I1da03a88f:Add eLayerIsDisplayDecoration flag
I7f22dfd03:Add/plumb SurfaceControl.DISPLAY_DECORATION

Change-Id: I7238bcc96325873ec7dbdd42894192c48e7cf92e