drm_hwcomposer: Allow layer transforms

They are very much valid now. I think this is just leftover?

BUG=chrome-os-partner:42717
TEST=test rotation, it doesn't lock up

Change-Id: I4cd96ae91c91452ef2be3cb3b07c123ce38ed576
diff --git a/drmdisplaycomposition.cpp b/drmdisplaycomposition.cpp
index c7168c0..c989494 100644
--- a/drmdisplaycomposition.cpp
+++ b/drmdisplaycomposition.cpp
@@ -178,8 +178,6 @@
 
   for (size_t layer_index = 0; layer_index < num_layers; layer_index++) {
     hwc_layer_1_t *layer = &layers[layer_indices[layer_index]];
-    if (layer->transform != 0)
-      return -EINVAL;
 
     native_handle_t *handle_copy = dup_buffer_handle(layer->handle);
     if (handle_copy == NULL) {