nvme: move setting the write cache flags out of nvme_set_queue_limits

nvme_set_queue_limits is used on the admin queue and all gendisks
including hidden ones that don't support block I/O.  The write cache
setting on the other hand only makes sense for block I/O.  Move the
blk_queue_write_cache call to nvme_update_ns_info_block instead.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Max Gurtovoy <mgurtovoy@nvidia.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>