platforms/drm: create gbm device in DrmGpu
Atomic tests need to use gbm buffers for accurate results. As the egl backends only get created after the initial updateOutputs
we need to create the gbm device in DrmGpu.
Atomic tests need to use gbm buffers for accurate results. As the egl backends only get created after the initial updateOutputs
we need to create the gbm device in DrmGpu.