nvme: add NVME_REQ_CANCELLED flag in nvme_cancel_request()

NVME_REQ_CANCELLED is translated into -EINTR in nvme_submit_sync_cmd(),
so we should be setting this flags during nvme_cancel_request() to
ensure that the callers to nvme_submit_sync_cmd() will get the correct
error code when the controller is reset.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Chao Leng <lengchao@huawei.com>
Reviewed-by: Daniel Wagner <dwagner@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>