[ Upstream commit 14a1336e6fff47dd1028b484d6c802105c58e2ee ]

Without CONFIG_NVME_MULTIPATH enabled a multi-port subsystem might
show up as invididual devices and cause problems, warn about it.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NSagi Grimberg <sagi@grimberg.me>
Signed-off-by: NSasha Levin <sashal@kernel.org>