drm/i915/guc: Rework and simplify locking

Rework and simplify the locking with GuC subission. Drop
sched_state_no_lock and move all fields under the guc_state.sched_state
and protect all these fields with guc_state.lock . This requires
changing the locking hierarchy from guc_state.lock -> sched_engine.lock
to sched_engine.lock -> guc_state.lock.

v2:
 (Daniele)
  - Don't check fields outside of lock during sched disable, check less
    fields within lock as some of the outside are no longer needed

Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210909164744.31249-18-matthew.brost@intel.com

drivers/gpu/drm/i915/gt/intel_context_types.h

@@ -161,7 +161,7 @@ struct intel_context {
 		 * sched_state: scheduling state of this context using GuC
 		 * submission
 		 */
-		u16 sched_state;
+		u32 sched_state;
 		/*
 		 * fences: maintains of list of requests that have a submit
 		 * fence related to GuC submission
@@ -178,9 +178,6 @@ struct intel_context {
 		struct list_head requests;
 	} guc_active;
 
-	/* GuC scheduling state flags that do not require a lock. */
-	atomic_t guc_sched_state_no_lock;
-
 	/* GuC LRC descriptor ID */
 	u16 guc_id;