wifi: iwlwifi: avoid scheduling restart during restart

When a restart is in progress, it can be async due to the next
worker being scheduled in mac80211 (restart work) or the driver
itself (reprobe). Avoid scheduling another restart during this
period.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://patch.msgid.link/20250430151952.db428503ec3c.I3f2be3d72a9d40cfb4e697cdab1cd2866a9262bc@changeid