iwlwifi: mvm: reserve bandwidth for low-latency interface

If there is/are interface(s) in low-latency mode, reserve a
percentage (currently 64%) of the quota for that binding to
improve the quality of service for those interfaces. However,
if there's more than one binding that has low-latency, then
give up and don't reserve, we can't allocate more than 100%.

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