drm/amdgpu: keep all fences in an RCU protected array v2

Just keep all HW fences in a RCU protected array as a
first step to replace the wait queue.

v2: update commit message, move fixes into separate patch.

Signed-off-by: Christian König <christian.koenig@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Chunming Zhou <david1.zhou@amd.com>
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index 26b1378..2fea597 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -393,6 +393,8 @@
 	unsigned			irq_type;
 	struct timer_list		fallback_timer;
 	wait_queue_head_t		fence_queue;
+	unsigned			num_fences_mask;
+	struct fence			**fences;
 };
 
 /* some special values for the owner field */