platformdrmgeneric: get the gralloc usage directly from the handle

There's no point in using a gralloc perform() op to retrieve the usage as
it is already stored in the handle like width, height, format, etc. So just
copy it to the hwc_drm_bo_t and get it directly.

Signed-off-by: Rob Herring <robh@kernel.org>
Reviewed-by: Robert Foss <robert.foss@collabora.com>
Tested-by: Robert Foss <robert.foss@collabora.com>
diff --git a/platformdrmgeneric.cpp b/platformdrmgeneric.cpp
index aa3d0fa..741d42b 100644
--- a/platformdrmgeneric.cpp
+++ b/platformdrmgeneric.cpp
@@ -116,6 +116,7 @@
   bo->width = gr_handle->width;
   bo->height = gr_handle->height;
   bo->format = ConvertHalFormatToDrm(gr_handle->format);
+  bo->usage = gr_handle->usage;
   bo->pitches[0] = gr_handle->stride;
   bo->gem_handles[0] = gem_handle;
   bo->offsets[0] = 0;