gpu: host1x: Set DMA ops on device creation

Currently host1x-instanciated devices have their dma_ops left to NULL,
which makes any DMA operation (like buffer import) on ARM64 fallback
to the dummy_dma_ops and fail with an error.

This patch calls of_dma_configure() with the host1x node when creating
such a device, so the proper DMA operations are set.

Suggested-by: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>