nvme: change shutdown timeout setting message

User visible messages containing the word "timeout" can be alarming.
This one from nvme is just reporting a potentially informative device
configuration, and everything is working as designed. Change the text to
report the less concerning "D3 entry latency", which is where this value
comes from anyway.

Reported-by: Len Brown <lenb@kernel.org>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>