isisd: fix a typo in a log message

Signed-off-by: Christian Franke <chris@opensourcerouting.org>
Acked-by: Donald Sharp <sharpd@cumulusnetworks.com>
diff --git a/isisd/isis_pdu.c b/isisd/isis_pdu.c
index 7408555..d63a8a6 100644
--- a/isisd/isis_pdu.c
+++ b/isisd/isis_pdu.c
@@ -1694,7 +1694,7 @@
           pdu_len > ISO_MTU(circuit) ||
           pdu_len > stream_get_endp (circuit->rcv_stream))
 	{
-	  zlog_warn ("Received a CSNP with bogus length %d", pdu_len);
+	  zlog_warn ("Received a PSNP with bogus length %d", pdu_len);
 	  return ISIS_WARNING;
 	}
     }