gpu/drm: Eliminate DRM_SCHED_PRIORITY_UNSET

Eliminate DRM_SCHED_PRIORITY_UNSET, value of -2, whose only user was
amdgpu. Furthermore, eliminate an index bug, in that when amdgpu boots, it
calls drm_sched_entity_init() with DRM_SCHED_PRIORITY_UNSET, which uses it to
index sched->sched_rq[].

Cc: Alex Deucher <Alexander.Deucher@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Signed-off-by: Luben Tuikov <luben.tuikov@amd.com>
Acked-by: Alex Deucher <Alexander.Deucher@amd.com>
Link: https://lore.kernel.org/r/20231017035656.8211-2-luben.tuikov@amd.com

drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c

@@ -64,7 +64,8 @@ amdgpu_ctx_to_drm_sched_prio(int32_t ctx_prio)
 {
 	switch (ctx_prio) {
 	case AMDGPU_CTX_PRIORITY_UNSET:
-		return DRM_SCHED_PRIORITY_UNSET;
+		pr_warn_once("AMD-->DRM context priority value UNSET-->NORMAL");
+		return DRM_SCHED_PRIORITY_NORMAL;
 
 	case AMDGPU_CTX_PRIORITY_VERY_LOW:
 		return DRM_SCHED_PRIORITY_MIN;

include/drm/gpu_scheduler.h

@@ -68,8 +68,7 @@ enum drm_sched_priority {
 	DRM_SCHED_PRIORITY_HIGH,
 	DRM_SCHED_PRIORITY_KERNEL,
 
-	DRM_SCHED_PRIORITY_COUNT,
-	DRM_SCHED_PRIORITY_UNSET = -2
+	DRM_SCHED_PRIORITY_COUNT
 };
 
 /* Used to chose between FIFO and RR jobs scheduling */