Timeslices between multiple context is supported via
guc scheduling. Add sysfs entry to provide user defined
timeslice duration to guc scheduling.

The timeslice duration can be adjusted per-engine class using,

/sys/class/drm/cardX/device/tileN/gtN/engines/ccs/timeslice_duration_us

V8:
  - Rebase
V7:
  - Rebase to use s/xe_engine/xe_hw_engine/ - Matt
V6:
  - Remove duration validation, not relevant - Niranjana
V5:
  - Rebase to replace hw engine with eclass interface
V4:
  - Rebase to per class engine props interface
V3:
  - Rebase
  - Update commit messge to add tile
V2:
  - Rebase
Reviewed-by: Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Tejas Upadhyay <tejas.upadhyay@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>