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>

Documentation/ABI/testing/debugfs-driver-habanalabs

@@ -16,7 +16,16 @@ Description:    Allow the root user to disable/enable in runtime the clock
                 gating mechanism in Gaudi. Due to how Gaudi is built, the
                 clock gating needs to be disabled in order to access the
                 registers of the TPC and MME engines. This is sometimes needed
-                during debug by the user and hence the user needs this option
+                during debug by the user and hence the user needs this option.
+                The user can supply a bitmask value, each bit represents
+                a different engine to disable/enable its clock gating feature.
+                The bitmask is composed of 20 bits:
+                0  -  7 : DMA channels
+                8  - 11 : MME engines
+                12 - 19 : TPC engines
+                The bit's location of a specific engine can be determined
+                using (1 << GAUDI_ENGINE_ID_*). GAUDI_ENGINE_ID_* values
+                are defined in uapi habanalabs.h file in enum gaudi_engine_id
 
 What:           /sys/kernel/debug/habanalabs/hl<n>/command_buffers
 Date:           Jan 2019