iwlwifi: mvm: use dump worker during restart instead of sync dump

In restart flow, the driver requests HW restart from mac80211
and then mac80211 uses a worker to do the restart flow. In that flow a
sync dump is performed. Instead, schedule the dump worker before
requesting HW restart from mac80211. This approach simplifies the
restart flow.
Also, it is neeeded in order to differentiate between the handling of SW
and HW errors in a future commit.

Signed-off-by: Shahar S Matityahu <shahar.s.matityahu@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>