iproute2: spelling: noptmudisc -> nopmtudisc

Signed-off-by: Richard Godbee <richard@godbee.net>
diff --git a/ip/iptunnel.c b/ip/iptunnel.c
index 43f8585..40186d3 100644
--- a/ip/iptunnel.c
+++ b/ip/iptunnel.c
@@ -280,7 +280,7 @@
 		return -1;
 
 	if (p.iph.ttl && p.iph.frag_off == 0) {
-		fprintf(stderr, "ttl != 0 and noptmudisc are incompatible\n");
+		fprintf(stderr, "ttl != 0 and nopmtudisc are incompatible\n");
 		return -1;
 	}