ionic: rework and simplify handling of the queue stats block

Use a block of stats structs attached to the lif instead of
little ones attached to each qcq.  This simplifies our memory
management and gets rid of a lot of unnecessary indirection.

Signed-off-by: Shannon Nelson <snelson@pensando.io>
Signed-off-by: David S. Miller <davem@davemloft.net>