vty: Change the return type from enum to int

clang complained that different enums are mixed with the
return type and we actually want this to be an int now.
diff --git a/openbsc/src/libcommon/common_vty.c b/openbsc/src/libcommon/common_vty.c
index 186fbe0..a0674f0 100644
--- a/openbsc/src/libcommon/common_vty.c
+++ b/openbsc/src/libcommon/common_vty.c
@@ -35,7 +35,7 @@
 #include <osmocom/vty/vty.h>
 
 
-enum node_type bsc_vty_go_parent(struct vty *vty)
+int bsc_vty_go_parent(struct vty *vty)
 {
 	switch (vty->node) {
 	case GSMNET_NODE: