net/bnxt: skip get statistics for stopped queues

net/bnxt: skip get statistics for stopped queues

An application using rte_flow may define a large number of queues
but only use a small subset of them at any one time.

Since querying the status of each queue requires a request/spin/reply
with the firmware, optimize by skipping the request for queues not
running.
For those queues the statistics will be 0.

This cuts the cost of single xstats query in half and has even
bigger gain for simple stats query.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Reviewed-by: Ajit Khaparde <ajit.khaparde@broadcom.com>