Revert "tun: call dev_get_valid_name() before register_netdevice()"

This reverts commit 0ad646c81b2182f7fa67ec0c8c825e0ee165696d.

As noticed by Jakub, this is no longer needed after
commit 11fc7d5a0a2d ("tun: fix memory leak in error path")

This no longer exports dev_get_valid_name() for the exclusive
use of tun driver.

Suggested-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
diff --git a/net/core/dev.c b/net/core/dev.c
index 7d05e04..8bc3dce 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1249,8 +1249,8 @@ int dev_alloc_name(struct net_device *dev, const char *name)
 }
 EXPORT_SYMBOL(dev_alloc_name);
 
-int dev_get_valid_name(struct net *net, struct net_device *dev,
-		       const char *name)
+static int dev_get_valid_name(struct net *net, struct net_device *dev,
+			      const char *name)
 {
 	BUG_ON(!net);
 
@@ -1266,7 +1266,6 @@ int dev_get_valid_name(struct net *net, struct net_device *dev,
 
 	return 0;
 }
-EXPORT_SYMBOL(dev_get_valid_name);
 
 /**
  *	dev_change_name - change name of a device