bnx2x: Don't receive packets when the napi budget == 0

Processing any incoming packets with a with a napi budget of 0
is incorrect driver behavior.

This matters as netpoll will shortly call drivers with a budget of 0
to avoid receive packet processing happening in hard irq context.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c

@@ -872,6 +872,8 @@ static int bnx2x_rx_int(struct bnx2x_fastpath *fp, int budget)
 	if (unlikely(bp->panic))
 		return 0;
 #endif
+	if (budget <= 0)
+		return rx_pkt;
 
 	bd_cons = fp->rx_bd_cons;
 	bd_prod = fp->rx_bd_prod;