Fix various compiler warnings in hnb-gw code

Since we finally started to use -Wall, the related warnings became
visible.

Change-Id: I516700eab2aa7c3412dd62775c4960aed9d4b682
diff --git a/src/hnbgw_vty.c b/src/hnbgw_vty.c
index f504dd5..3d16970 100644
--- a/src/hnbgw_vty.c
+++ b/src/hnbgw_vty.c
@@ -18,6 +18,8 @@
  *
  */
 
+#include <string.h>
+
 #include <osmocom/vty/command.h>
 
 #include <osmocom/iuh/vty.h>
@@ -233,9 +235,6 @@
 
 static int config_write_hnbgw_iucs(struct vty *vty)
 {
-	const char *addr;
-	uint16_t port;
-
 	if (!g_hnb_gw->config.iucs_remote_addr_name)
 		return CMD_SUCCESS;
 
@@ -248,9 +247,6 @@
 
 static int config_write_hnbgw_iups(struct vty *vty)
 {
-	const char *addr;
-	uint16_t port;
-
 	if (!g_hnb_gw->config.iups_remote_addr_name)
 		return CMD_SUCCESS;