drm/xe: Separate out sched/deregister_done handling

drm/xe: Separate out sched/deregister_done handling

Abstract out the core part of sched_done and deregister_done handlers
to separate functions to decouple them from any protocol error handling
part and make them more readable.

Signed-off-by: Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240319184153.16667-1-niranjana.vishwanathapura@intel.com