drm/i915/guc: Remove intel_context:number_committed_requests counter

With the introduction of the delayed disable-sched behavior,
we use the GuC's xarray of valid guc-id's as a way to
identify if new requests had been added to a context
when the said context is being checked for closure.

Additionally that prior change also closes the race for when
a new incoming request fails to cancel the pending
delayed disable-sched worker.

With these two complementary checks, we see no more
use for intel_context:guc_state:number_committed_requests.

Signed-off-by: Alan Previn <alan.previn.teres.alexis@intel.com>
Reviewed-by: John Harrison <John.C.Harrison@Intel.com>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221006225121.826257-3-alan.previn.teres.alexis@intel.com