bnxt_en: Refactor the hash table logic for ntuple filters.

Generalize the ethtool logic that walks the ntuple hash table now that
we have the common bnxt_filter_base structure.  This will allow the code
to easily extend to cover user defined ntuple or ether filters.

Reviewed-by: Vasundhara Volam <vasundhara-v.volam@broadcom.com>
Reviewed-by: Andy Gospodarek <andrew.gospodarek@broadcom.com>
Reviewed-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>