ethernet/realtek: Replace synchronize_sched() with synchronize_rcu()

Now that synchronize_rcu() waits for preempt-disable regions of code
as well as RCU read-side critical sections, synchronize_sched() can be
replaced by synchronize_rcu().  This commit therefore makes this change.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Realtek linux nic maintainers <nic_swsd@realtek.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: <netdev@vger.kernel.org>

drivers/net/ethernet/realtek/8139too.c

@@ -1661,7 +1661,7 @@ static void rtl8139_tx_timeout_task (struct work_struct *work)
 
 	napi_disable(&tp->napi);
 	netif_stop_queue(dev);
-	synchronize_sched();
+	synchronize_rcu();
 
 	netdev_dbg(dev, "Transmit timeout, status %02x %04x %04x media %02x\n",
 		   RTL_R8(ChipCmd), RTL_R16(IntrStatus),

drivers/net/ethernet/realtek/r8169.c

@@ -5866,7 +5866,7 @@ static void rtl_reset_work(struct rtl8169_private *tp)
 
 	napi_disable(&tp->napi);
 	netif_stop_queue(dev);
-	synchronize_sched();
+	synchronize_rcu();
 
 	rtl8169_hw_reset(tp);
 
@@ -6609,7 +6609,7 @@ static void rtl8169_down(struct net_device *dev)
 	rtl8169_rx_missed(dev);
 
 	/* Give a racing hard_start_xmit a few cycles to complete. */
-	synchronize_sched();
+	synchronize_rcu();
 
 	rtl8169_tx_clear(tp);