bnxt_en: Add new hardware RFS mode.

The existing hardware RFS mode uses one hardware RSS context block
per ring just to calculate the RSS hash.  This is very wasteful and
prevents VF functions from using it.  The new hardware mode shares
the same hardware RSS context for RSS placement and RFS steering.
This allows VFs to enable RFS.

Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>