drm/amdgpu: fix a build warning by a typo in amdgpu_gfx.c

This should be a typo when intruducing multi-xx support.
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Guchun Chen <guchun.chen@amd.com>
Cc: Le Ma <le.ma@amd.com>
Reviewed-by: Le Ma <le.ma@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -470,8 +470,8 @@ void amdgpu_gfx_mqd_sw_fini(struct amdgpu_device *adev, int xcc_id)
 
 	for (i = 0; i < adev->gfx.num_compute_rings; i++) {
 		j = i + xcc_id * adev->gfx.num_compute_rings;
-		ring = &adev->gfx.compute_ring[i];
-		kfree(adev->gfx.mec.mqd_backup[i]);
+		ring = &adev->gfx.compute_ring[j];
+		kfree(adev->gfx.mec.mqd_backup[j]);
 		amdgpu_bo_free_kernel(&ring->mqd_obj,
 				      &ring->mqd_gpu_addr,
 				      &ring->mqd_ptr);