Fix the resume code path in iwm(4) to no longer call iwm_stop() before

Fix the resume code path in iwm(4) to no longer call iwm_stop() before
initializing the hardware. Prevents "acquiring device failed" messages
during resume. Also, start the hardware up in DVACT_RESUME already and
verify that it has started by the time we reach DVACT_WAKEUP, before
scheduling the iwm_init_task which loads firmware etc.
With help from deraadt@
test & ok tb@