net/bnxt: fix Rx queue start/stop for Thor based NICs

net/bnxt: fix Rx queue start/stop for Thor based NICs

Controller-specific handling is required for Thor-based NICs when
stopping or starting a receive queue, otherwise packet reception
may not be reliably resumed when a stopped receive queue is
restarted:
  - The VNIC default receive ring needs to be recomputed when a
    receive queue is stopped or started.
  - When stopping the last (or only) receive queue for a given
    VNIC, ensure that no packets can reach the default receive
    ring by temporarily setting the VNIC MRU to zero.

Fixes: f8168ca0e690 ("net/bnxt: support thor controller")
Cc: stable@dpdk.org
Signed-off-by: Lance Richardson <lance.richardson@broadcom.com>
Reviewed-by: Ajit Khaparde <ajit.khaparde@broadcom.com>