nvme: enable FDP support

nvme: enable FDP support

Flexible Data Placement (FDP), as ratified in TP 4146a, allows the host
to control the placement of logical blocks so as to reduce the SSD WAF.

Userspace can send the data lifetime information using the write hints.
The SCSI driver (sd) can already pass this information to the SCSI
devices. This patch does the same for NVMe.

Fetch the placement-identifiers if the device supports FDP.
The incoming write-hint is mapped to a placement-identifier, which in
turn is set in the DSPEC field of the write command.

Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
Signed-off-by: Hui Qi <hui81.qi@samsung.com>
Signed-off-by: Nitesh Shetty <nj.shetty@samsung.com>
Nacked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>