This patch converts tg3_start_xmit_dma_bug() to accomodate multiple NAPI
instances.  This is prep work for a later patch in this series.
Signed-off-by: Matt Carlson <mcarlson@broadcom.com>
Reviewed-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>