bridge: fix string length warning

Gcc-10 complains about possible string length overflow.
This can't happen Ethernet address format is always limited to
18 characters or less. Just resize the temp buffer.

Fixes: 70dfb0b883 ("iplink: bridge: export bridge_id and designated_root")
Cc: nikolay@cumulusnetworks.com
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>

ip/iplink_bridge.c

@@ -74,7 +74,7 @@ static void explain(void)
 
 void br_dump_bridge_id(const struct ifla_bridge_id *id, char *buf, size_t len)
 {
-	char eaddr[32];
+	char eaddr[18];
 
 	ether_ntoa_r((const struct ether_addr *)id->addr, eaddr);
 	snprintf(buf, len, "%.2x%.2x.%s", id->prio[0], id->prio[1], eaddr);