video: adf: add informational flags to interfaces

Informational flags don't affect ADF directly but may be useful to
clients.  Currently used to indicate primary and external displays.

Change-Id: I343c7f0148da0869244c8e818350e9855525df85
Signed-off-by: Greg Hackmann <ghackmann@google.com>
Git-commit: 27e7183c5aa432bfd6a99e6164761eae3917748b
Git-Repo: https://android.googlesource.com/kernel/common.git


Signed-off-by: Ian Maund <imaund@codeaurora.org>