iwlwifi: mvm: add support for net detect

Add the net detect WoWLAN flag to indicate support and use the
nd_config from the WoWLAN configuration to start net detect, if it is
set.  The WoWLAN configuration takes precedence over the debugfs
configuration.

Signed-off-by: Luciano Coelho <luciano.coelho@intel.com>
Reviewed-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>