nvmet: fix data units read and written counters in SMART log

In nvme spec 1.3 there is a definition for data write/read counters
from SMART log, (See section 5.14.1.2):
	This value is reported in thousands (i.e., a value of 1
	corresponds to 1000 units of 512 bytes read) and is rounded up.

However, in nvme target where value is reported with actual units,
but not thousands of units as the spec requires.

Signed-off-by: Tom Wu <tomwu@mellanox.com>
Reviewed-by: Israel Rukshin <israelr@mellanox.com>
Reviewed-by: Max Gurtovoy <maxg@mellanox.com>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>