ice: get rid of per-tc flow in Tx queue configuration routines

There's no reason for treating DCB as first class citizen when configuring
the Tx queues and going through TCs. Reverse the logic and base the
configuration logic on rings, which is the object of interest anyway.

Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>