nvme-pci: move more teardown work to nvme_remove

nvme_dbbuf_dma_free frees dma coherent memory, so it must not be called
after ->remove has returned.  Fortunately there is no way to use it
after shutdown as no more I/O is possible so it can be moved.  Similarly
the iod_mempool can't be used for a device kept alive after shutdown, so
move it next to freeing the PRP pools.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Tested-by Gerd Bayer <gbayer@linxu.ibm.com>

drivers/nvme/host/pci.c

@@ -2773,9 +2773,7 @@ static void nvme_pci_free_ctrl(struct nvme_ctrl *ctrl)
 {
 	struct nvme_dev *dev = to_nvme_dev(ctrl);
 
-	nvme_dbbuf_dma_free(dev);
 	nvme_free_tagset(dev);
-	mempool_destroy(dev->iod_mempool);
 	put_device(dev->dev);
 	kfree(dev->queues);
 	kfree(dev);
@@ -3227,7 +3225,9 @@ static void nvme_remove(struct pci_dev *pdev)
 	nvme_dev_disable(dev, true);
 	nvme_free_host_mem(dev);
 	nvme_dev_remove_admin(dev);
+	nvme_dbbuf_dma_free(dev);
 	nvme_free_queues(dev, 0);
+	mempool_destroy(dev->iod_mempool);
 	nvme_release_prp_pools(dev);
 	nvme_dev_unmap(dev);
 	nvme_uninit_ctrl(&dev->ctrl);