iwlwifi: mvm: add support for 8 level scan priority API

Add support for scan priority API with 8 levels instead of the
existing 3 levels. This API is needed to define the priority of
new ooc activities, e.g. gscan.
Add a TLV flag to indicate if the new API is supported so that
devices that does not support the new API will continue to use
the old one.

Signed-off-by: Avraham Stern <avraham.stern@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>