Removing private system ui flags from status bar flags logic.

- Prevent third party apps from inadvertently changing internal SystemUI
  flags through a call to setSystemUiVisibility().  These flags are only
  set in the individual SystemUI components and can be updated in WMS
  directly.

Bug: 29875297
Change-Id: I5ea238c8fb16a0eccd6e993d95a912acb359cee6
12 files changed