drm_hwcomposer: Allow NULL crtcs in display composition

In cases where we have displays which do not have a mode,
the crtc will be NULL. This shouldn't fail the composition
initialization.

Change-Id: I1a6acb72cd3f614b5a7c854ba61be1539efa4bea
Signed-off-by: Sean Paul <seanpaul@chromium.org>
diff --git a/drmcomposition.cpp b/drmcomposition.cpp
index fad131d..3612972 100644
--- a/drmcomposition.cpp
+++ b/drmcomposition.cpp
@@ -54,11 +54,10 @@
       ALOGE("Failed to allocate new display composition\n");
       return -ENOMEM;
     }
+
+    // If the display hasn't been modeset yet, this will be NULL
     DrmCrtc *crtc = drm_->GetCrtcForDisplay(display);
-    if (!crtc) {
-      ALOGE("Failed to find crtc for display %d", display);
-      return -ENODEV;
-    }
+
     int ret = composition_map_[(*iter)->display()]->Init(drm_, crtc, importer_);
     if (ret) {
       ALOGE("Failed to init display composition for %d", (*iter)->display());