nvme: introduce change ptpl and iekey definition

This is for the next tuning pr code more readble patch, make
linux/nvme.h's changes separately.

Signed-off-by: Guixin Liu <kanie@linux.alibaba.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>