For freedreno DDX, we have to create the scanout GEM bo in a special way
(until we have our own KMS/DRM kernel driver.. and even then for
phones/tablets you probably need to use the android drivers if you don't
want to port the lcd panel driver support).  The easiest way to handle
this is let the DDX create the scanout bo, and then create the xa
surface from that.

Signed-off-by: Rob Clark <robclark@freedesktop.org>