iwlwifi: mvm: fix quota allocation

Divide the maximal quota between all the data interfaces even in the
case of a single low latency binding without any other non low latency
interfaces, so that afterwards the quota allocation (which considers
the number of data interfaces) will be correct.

Signed-off-by: Ilan Peer <ilan.peer@intel.com>
Reviewed-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>