habanalabs: set clock gating per engine

For debugging purposes, we need to allow the root user better control of
the clock gating feature of the DMA and compute engines. Therefore, change
the clock gating debugfs interface to be bitmask instead of true/false.
Each bit represents a different engine, according to gaudi_engine_id enum.

See debugfs documentation for more details.

Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>
Reviewed-by: Omer Shpigelman <oshpigelman@habana.ai>