habanalabs: move reset workqueue to be under hl_device
'struct hl_device_reset_work' is used as a wrapper for the reset work
and its parameters, including the reset workqueue on which it runs.
In a future commit, another reset related work with similar parameters
is going to be added, but it won't use the reset workqueue.
As in any case there is a single reset workqueue, and to allow the resue
of this structure, move the reset workqueue to 'struct hl_device'.