bnxt_en: Do not process completion entries after fatal condition detected.

Once the firmware fatal condition is detected, we should cease
comminication with the firmware and hardware quickly even if there
are many completion entries in the completion rings.  This will
speed up the recovery process and prevent further I/Os that may
cause further exceptions.

Do not proceed in the NAPI poll function if fatal condition is
detected.  Call napi_complete() and return without arming interrupts.
Cleanup of all rings and reset are imminent.

Reviewed-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Reviewed-by: Vasundhara Volam <vasundhara-v.volam@broadcom.com>
Reviewed-by: Edwin Peer <edwin.peer@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>