This patch addresses an irq free warning and null pointer dereference
error problem when nvme devices got timeout error during initialization.
This problem happens when nvme_timeout() function is called while
nvme_reset_work() is still in execution. This patch fixed the problem by
setting flag of the problematic request to NVME_REQ_CANCELLED before
calling nvme_dev_disable() to make sure __nvme_submit_sync_cmd() returns
an error code and let nvme_submit_sync_cmd() fail gracefully.
The following is console output.