drm/amdgpu: clean up unused variable about ring lru

clean up unused variable:
1. ring_lru_list
2. ring_lru_list_lock

related-commit:
drm/amdgpu: remove ring lru handling
Signed-off-by: NKevin Wang <kevin1.wang@amd.com>
Reviewed-by: NChristian König <christian.koenig@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu.h

@@ -957,9 +957,6 @@ struct amdgpu_device {
 	/* link all shadow bo */
 	struct list_head                shadow_list;
 	struct mutex                    shadow_list_lock;
-	/* keep an lru list of rings by HW IP */
-	struct list_head		ring_lru_list;
-	spinlock_t			ring_lru_list_lock;
 
 	/* record hw reset is performed */
 	bool has_hw_reset;

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

@@ -2988,9 +2988,6 @@ int amdgpu_device_init(struct amdgpu_device *adev,
 	INIT_LIST_HEAD(&adev->shadow_list);
 	mutex_init(&adev->shadow_list_lock);
 
-	INIT_LIST_HEAD(&adev->ring_lru_list);
-	spin_lock_init(&adev->ring_lru_list_lock);
-
 	INIT_DELAYED_WORK(&adev->delayed_init_work,
 			  amdgpu_device_delayed_init_work_handler);
 	INIT_DELAYED_WORK(&adev->gfx.gfx_off_delay_work,