net: drop the unused helper skb_ext_get()

Such helper is currently unused, and skb extension users are
better off using skb_ext_add()/skb_ext_del(). So let's drop
it.
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Acked-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/skbuff.h

@@ -3938,16 +3938,6 @@ static inline void skb_ext_put(struct sk_buff *skb)
 		__skb_ext_put(skb->extensions);
 }
 
-static inline void skb_ext_get(struct sk_buff *skb)
-{
-	if (skb->active_extensions) {
-		struct skb_ext *ext = skb->extensions;
-
-		if (ext)
-			refcount_inc(&ext->refcnt);
-	}
-}
-
 static inline void __skb_ext_copy(struct sk_buff *dst,
 				  const struct sk_buff *src)
 {
@@ -3995,7 +3985,6 @@ static inline void *skb_ext_find(const struct sk_buff *skb, enum skb_ext_id id)
 }
 #else
 static inline void skb_ext_put(struct sk_buff *skb) {}
-static inline void skb_ext_get(struct sk_buff *skb) {}
 static inline void skb_ext_del(struct sk_buff *skb, int unused) {}
 static inline void __skb_ext_copy(struct sk_buff *d, const struct sk_buff *s) {}
 static inline void skb_ext_copy(struct sk_buff *dst, const struct sk_buff *s) {}