nvme: move the CSI sanity check into nvme_ns_report_zones

Move the CSI check into nvme_ns_report_zones to clean up the code
a little bit and prepare for further refactoring.

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