inet fragments: fix sparse warning: context imbalance

Impact: Attribute function with __releases(...)

Fix this sparse warning:
  net/ipv4/inet_fragment.c:276:35: warning: context imbalance in 'inet_frag_find' - unexpected unlock

Signed-off-by: Hannes Eder <hannes@hanneseder.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/inet_fragment.c b/net/ipv4/inet_fragment.c
index 6c52e08..eaf3e2c 100644
--- a/net/ipv4/inet_fragment.c
+++ b/net/ipv4/inet_fragment.c
@@ -267,6 +267,7 @@
 
 struct inet_frag_queue *inet_frag_find(struct netns_frags *nf,
 		struct inet_frags *f, void *key, unsigned int hash)
+	__releases(&f->lock)
 {
 	struct inet_frag_queue *q;
 	struct hlist_node *n;