accel/habanalabs: use memhash_node_export_put() in hl_release_dmabuf()

The same mutex lock/unlock and counter decrementing in
hl_release_dmabuf() is already done in the memhash_node_export_put()
helper function.

Signed-off-by: Tomer Tayar <ttayar@habana.ai>
Reviewed-by: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Oded Gabbay <ogabbay@kernel.org>
Reviewed-by: Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com>