dhcpd: string reuse

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/networking/udhcp/dhcpd.c b/networking/udhcp/dhcpd.c
index 79677ee..2671ea3 100644
--- a/networking/udhcp/dhcpd.c
+++ b/networking/udhcp/dhcpd.c
@@ -226,7 +226,7 @@
 
 	init_packet(&packet, oldpacket, DHCPNAK);
 
-	log1("sending NAK");
+	log1("sending %s", "NAK");
 	send_packet(&packet, /*force_bcast:*/ 1);
 }