[NET]: Replace schedule_timeout() with msleep() in netdev_wait_allrefs()

Description: Use msleep() instead of schedule_timeout() to guarantee the task
delays as expected. The current code uses TASK_INTERRUPTIBLE, but does not
respond to signals, so msleep() should be ok.
Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/dev.c

@@ -108,6 +108,7 @@
 #include <linux/kallsyms.h>
 #include <linux/netpoll.h>
 #include <linux/rcupdate.h>
+#include <linux/delay.h>
 #ifdef CONFIG_NET_RADIO
 #include <linux/wireless.h>		/* Note : will define WIRELESS_EXT */
 #include <net/iw_handler.h>
@@ -2899,8 +2900,7 @@ static void netdev_wait_allrefs(struct net_device *dev)
 			rebroadcast_time = jiffies;
 		}
 
-		current->state = TASK_INTERRUPTIBLE;
-		schedule_timeout(HZ / 4);
+		msleep(250);
 
 		if (time_after(jiffies, warning_time + 10 * HZ)) {
 			printk(KERN_EMERG "unregister_netdevice: "