net: ipv6: fix missing dst ref drop in ila lwtunnel

Add missing skb_dst_drop() to drop reference to the old dst before
adding the new dst to the skb.

Fixes: 79ff2fc ("ila: Cache a route to translated address")
Cc: Tom Herbert <tom@herbertland.com>
Signed-off-by: Justin Iurman <justin.iurman@uliege.be>
Link: https://patch.msgid.link/20250305081655.19032-1-justin.iurman@uliege.be
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

net/ipv6/ila/ila_lwt.c

@@ -96,6 +96,7 @@ static int ila_output(struct net *net, struct sock *sk, struct sk_buff *skb)
 		}
 	}
 
+	skb_dst_drop(skb);
 	skb_dst_set(skb, dst);
 	return dst_output(net, sk, skb);