iwlwifi: mvm: clarify stop_count, remove transport_stopped

The queue handling is a bit unclear - we have an array for
stop_count[IWL_MAX_HW_QUEUES] but indices really are the
mac80211 queue numbers. Change the array to be only of the
right size for mac80211 queues (IEEE80211_MAX_QUEUES) and
rename it to be clearer.

While at it, also remove the unused transport queue stop
bitmap in mvm.

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