drm/xe: Deprecate XE_EXEC_QUEUE_SET_PROPERTY_COMPUTE_MODE implementation

We are going to remove XE_EXEC_QUEUE_SET_PROPERTY_COMPUTE_MODE from the
uAPI, deprecate the implementation first by making
XE_EXEC_QUEUE_SET_PROPERTY_COMPUTE_MODE a NOP. After removal of
XE_EXEC_QUEUE_SET_PROPERTY_COMPUTE_MODE the proper is simply inherented
from the VM.

v2:
 - Update commit message with explaination of removal (Niranjana)

Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>