NVMe: init scatter/gather lists

Forgot to initialize the scatter/gatter list. This result in protection
fault when the mappings are set up with 2 or more segments.
NVMe: remove jiffies from iod

Timeouts are handled by the block layer. No neep to keep track within
the iod structure.
NVMe: Enable timeout handling again

timeouts handling where disabled while debugging timeouts that occurred
after a command was completed successfully.