smsc911x: timeout reaches -1

With a postfix decrement the timeout will reach -1 rather than 0,
so the warning will not be issued.
Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Acked-by: Steve Glendinning <steve.glendinning@smsc.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/smsc911x.c

@@ -953,7 +953,7 @@ smsc911x_rx_fastforward(struct smsc911x_data *pdata, unsigned int pktbytes)
 		do {
 			udelay(1);
 			val = smsc911x_reg_read(pdata, RX_DP_CTRL);
-		} while (timeout-- && (val & RX_DP_CTRL_RX_FFWD_));
+		} while (--timeout && (val & RX_DP_CTRL_RX_FFWD_));
 
 		if (unlikely(timeout == 0))
 			SMSC_WARNING(HW, "Timed out waiting for "