iwlwifi: mvm: the SCD byte count is a TLV flag

The SCD byte count layout is decided by the configuration
done in fw, it is then logical to export it as a TLV flag
and not per HW SKU.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>