i2400m implements dynamic work allocation and queueing mechanism in
i2400_schedule_work(); however, this is only used for reset and
recovery which can be served equally well with preallocated per device
works.
Replace i2400m_schedule_work() with two work structs in struct i2400m.
These works are explicitly canceled when the device is released making
calls to flush_scheduled_work(), which is being deprecated,
unnecessary.