iwlwifi: don't double-activate queue 4

The fourth queue (command queue) is already activated in
the loop above that also maps it to the command FIFO and
therefore doesn't need to be marked as activated again.
Also change the TODO comment to be accurate -- we need
to initialise the _queues_, not FIFOs, and map them to
device FIFOs.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>