net: Mark functions as static in core/dev.c

Mark functions as static in core/dev.c because they are not used outside
this file.

This eliminates the following warning in core/dev.c:
net/core/dev.c:2806:5: warning: no previous prototype for ‘__dev_queue_xmit’ [-Wmissing-prototypes]
net/core/dev.c:4640:5: warning: no previous prototype for ‘netdev_adjacent_sysfs_add’ [-Wmissing-prototypes]
net/core/dev.c:4650:6: warning: no previous prototype for ‘netdev_adjacent_sysfs_del’ [-Wmissing-prototypes]

Signed-off-by: Rashika Kheria <[e-mail]>
Reviewed-by: Josh Triplett <[e-mail]>
Reviewed-by: Veaceslav Falico <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/core/dev.c

···
  *      the BH enable code must have IRQs enabled so that it will not deadlock.
  *          --BLG
  */
-int __dev_queue_xmit(struct sk_buff *skb, void *accel_priv)
+static int __dev_queue_xmit(struct sk_buff *skb, void *accel_priv)
 {
 	struct net_device *dev = skb->dev;
 	struct netdev_queue *txq;
···
 }
 EXPORT_SYMBOL(netdev_master_upper_dev_get_rcu);
 
-int netdev_adjacent_sysfs_add(struct net_device *dev,
+static int netdev_adjacent_sysfs_add(struct net_device *dev,
 			      struct net_device *adj_dev,
 			      struct list_head *dev_list)
 {
···
 	return sysfs_create_link(&(dev->dev.kobj), &(adj_dev->dev.kobj),
 				 linkname);
 }
-void netdev_adjacent_sysfs_del(struct net_device *dev,
+static void netdev_adjacent_sysfs_del(struct net_device *dev,
 			       char *name,
 			       struct list_head *dev_list)
 {