habanalabs/gaudi2: new API to control engine cores running mode

The current flow of halting the engine cores is implemented by command
buffers built by the user space and sent towards the Driver.

This current flow is broken since the user space does not know when
the cores actually halt as sending a workload is async op.

Therefore the application can not free the memory that is mapped
to the engine cores.

This new API allows the user space to control the running mode. The
API call is sync (returns after the cores are set to the
requested mode).

Signed-off-by: Tal Cohen <talcohen@habana.ai>
Reviewed-by: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Oded Gabbay <ogabbay@kernel.org>