drm_hwcomposer: Add sanity check on display in SetLayers

Ensure that the displays given to SetLayers are actually drm displays
before referencing them in the composition_map_.

Change-Id: I87819cdb8f68ed09bf71b95dff149d5043931ffb
Signed-off-by: Sean Paul <seanpaul@chromium.org>
1 file changed