habanalabs: add driver support for internal cb scheduling

In order to support scnenarios in which driver needs access to
HW components but it cannot access them directly, we add support for
scheduling command buffers internally.
These command buffers will be transmitted upon next user command
submission context.

Signed-off-by: Ofir Bitton <obitton@habana.ai>
Reviewed-by: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Oded Gabbay <ogabbay@kernel.org>