hw/nvme: fix attachment of private namespaces

hw/nvme: fix attachment of private namespaces

Fix regression when attaching private namespaces that gets attached to
the wrong controller.

Keep track of the original controller "owner" of private namespaces, and
only attach if this matches on controller enablement.

Fixes: 6ccca4b6bb9f ("hw/nvme: rework csi handling")
Reported-by: Alan Adamson <alan.adamson@oracle.com>
Suggested-by: Alan Adamson <alan.adamson@oracle.com>
Signed-off-by: Klaus Jensen <k.jensen@samsung.com>
Tested-by: Alan Adamson <alan.adamson@oracle.com>
Reviewed-by: Alan Adamson <alan.adamson@oracle.com>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Message-ID: <20250408-fix-private-ns-v1-1-28e169b6b60b@samsung.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>