iwlagn: move traffic_log back to upper layer

The traffic log debugfs handlers were mistakenly moved to the
transport layer because they print the pointers of the Tx / Rx
queues. The pointers of the queues can be fetched by another debugfs
handler.
So bring the traffic log back to the upper layer and remove the part
that reads the Tx / Rx queues' pointers.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>