habanalabs: remove support to export dmabuf from handle

The API to the user which allows exporting DMA buffer from handle is
deprecated here. It was never used as it is relevant only for Gaudi2,
and the user stack has yet to add support for dmabuf in Gaudi2.

Looking forward, a modified API to export DMA buffer for ASICs that
supports virtual memory will be added.

Until the new API will be ready- exporting DMA buffer will not be
supported for ASICs with virtual memory.

Signed-off-by: Ohad Sharabi <osharabi@habana.ai>
Reviewed-by: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Oded Gabbay <ogabbay@kernel.org>