nvme: allow 64-bit results in passthru commands

It is not possible to get 64-bit results from the passthru commands,
what prevents from getting for the Capabilities (CAP) property value.

As a result, it is not possible to implement IOL's NVMe Conformance
test 4.3 Case 1 for Fabrics targets [1] (page 123).

This issue has been already discussed [2], but without a solution.

This patch solves the problem by adding new ioctls with a new
passthru structure, including 64-bit results. The older ioctls stay
unchanged.

[1] https://www.iol.unh.edu/sites/default/files/testsuites/nvme/UNH-IOL_NVMe_Conformance_Test_Suite_v11.0.pdf
[2] http://lists.infradead.org/pipermail/linux-nvme/2018-June/018791.html

Signed-off-by: Marta Rybczynska <marta.rybczynska@kalray.eu>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>