net/bnxt: add hierarchical flow counters

net/bnxt: add hierarchical flow counters

Add support for hierarchical flow counter accumulation.
In case of hierarchical flows, involving parent and child flows,
the child flow counters are aggregated to get the parent flow counter
information. This should help in cases where one ore more flows
is related to a previously offloaded flow.

Signed-off-by: Kishore Padmanabha <kishore.padmanabha@broadcom.com>
Reviewed-by: Shahaji Bhosle <sbhosle@broadcom.com>
Reviewed-by: Ajit Khaparde <ajit.khaparde@broadcom.com>