net: tipc: avoid possible garbage value

Clang static checker (scan-build) warning:
net/tipc/bcast.c:305:4:
The expression is an uninitialized value. The computed value will also
be garbage [core.uninitialized.Assign]
  305 |                         (*cong_link_cnt)++;
      |                         ^~~~~~~~~~~~~~~~~~

tipc_rcast_xmit() will increase cong_link_cnt's value, but cong_link_cnt
is uninitialized. Although it won't really cause a problem, it's better
to fix it.

Fixes: dca4a17d ("tipc: fix potential hanging after b/rcast changing")
Signed-off-by: Su Hui <suhui@nfschina.com>
Reviewed-by: Justin Stitt <justinstitt@google.com>
Link: https://patch.msgid.link/20240912110119.2025503-1-suhui@nfschina.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

net/tipc/bcast.c

@@ -320,8 +320,8 @@ static int tipc_mcast_send_sync(struct net *net, struct sk_buff *skb,
 {
 	struct tipc_msg *hdr, *_hdr;
 	struct sk_buff_head tmpq;
+	u16 cong_link_cnt = 0;
 	struct sk_buff *_skb;
-	u16 cong_link_cnt;
 	int rc = 0;
 
 	/* Is a cluster supporting with new capabilities ? */