nvme: fix implicit bool to flags conversion

nvme_map_user_request() takes flags as the last argument, but
nvme_uring_cmd_io() shoves a bool "vec" into it. It behaves as
expected because bool is converted to 0/1 and NVME_IOCTL_VEC is
defined as 1, but it's better to pass flags explicitly.

Fixes: 7b7fdb8e ("nvme: replace the "bool vec" arguments with flags in the ioctl path")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Anuj Gupta <anuj20.g@samsung.com>
Reviewed-by: Kanchan Joshi <joshi.k@samsung.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Caleb Sander Mateos <csander@purestorage.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>