iwlwifi: mvm: implement UMAC scan API

This API uses second CPU scan commands, and can support multiple
simultaneous scans.

Adding the new API, and adding new mechanisms to deal with up to
8 simultaneous scans instead of the old scan status.

New scan API requires scan configuration for default scan parameters,
adding it in _up flow. Also updating scan configuration after updating
valid scan antennas via debugfs.

Signed-off-by: David Spinadel <david.spinadel@intel.com>
Reviewed-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>