iwlagn: dont update bytecount table for command queue

The device doesn't use the bytecount table for the
command queue, only for aggregation queues to make
aggregation decisions. So don't update it for the
command queue (and we even updated it with wrong
values).

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>